Paul now proceeds to illustrate justification by faith apart from the law and works of the law in Romans 3, and uses the examples of Abraham and David, two ancestors of whom the Jews were especially proud.

William Newell explains that...

THE JEWS ESPECIALLY gloried in Abraham and David, -just as we all naturally glory in the assumed personal righteousness of great saints, as the ground of God's favor to them. But whatever blessing, says Paul, Abraham obtained, Scripture forbade the thought that he could glory before God; because he simply believed what God told him, that his seed should be in number like the stars of heaven. (Read Ge 15:6) Abraham gave God His proper glory as the God of truth. We cannot conceive of Abraham as boasting before his house and before the Hittites that he had performed an act creditable to himself in believing God! (Newell, William: Romans Verse by Verse)

What then (oun) in inductive Bible study is referred to as a term of conclusion and can also be translated "therefore". This term of conclusion connects the following argument with what Paul has been talking about in the third chapter. In the preceding chapter Paul had asked several rhetorical (for effect not expecting an answer) questions:

Where is boasting? (Romans 3:27,28)

Was God the God of the Jews only or of the Gentiles also? (Romans 3:29, 30)

Was the Law was nullified by salvation by faith? (Romans 3:31)

Rephrased, this verse would read

"Therefore, what shall we say that Abraham, our first father, has found according to the flesh, that is, by natural human effort?"

Paul appears to be utilizing a style of teaching referred to as "diatribe" which was no uncommonly used in ancient philosophical schools and is  characterized by rhetorical questions and imaginary interlocutors. Diatribes typically would include rhetorical questions such as “What shall we say then?” to mark transition to the next point.

"What then shall we say" is a rhetorical question, an approach which Paul is fond of (Ro 4:1; 6:1; 7:7; 8:31; 9:14, 30). In Romans he often uses this method in anticipation of an objection or to propose an inference. The rhetorical approach is used only by Paul in Romans in its "argumentative" portions (the first 11 chapters) and is not used in the last five chapters, which are exhortational.

The design of the first part of this chapter is to answer some of the objections which might be offered by a Jew to the statements in the preceding chapters. The first objection is stated in this verse. A Jew would naturally ask, if the view which Paul had stated was correct, what benefit could the Jew derive from his religion? This question is practically the same as in Chapter Three, "What advantage, then, has the Jew ?"

Paul like any good teacher then proceeds to illustrate the abstract truth of justification by faith apart from works (which he had just summarized in Ro3:21-31) using the example of faith in action in the life of Abraham (and David).

According to Jewish law, a question was settled by two or three witnesses. Paul calls two witnesses ("the Law and the Prophets" in Ro 3:21- note) from the OT to testify to justification through faith. In Romans 4 he brings these two witnesses to the stand so to speak, calling on "father Abraham" from the Law and the beloved David who was not only a king but a prophet, as attested by Peter in his sermon to the Jews at the feast of Pentecost, in which he declared

"Brethren, I may confidently say to you regarding the patriarch David that he both died and was buried, and his tomb is with us to this day... he was a prophet, and knew that GOD HAD SWORN TO HIM WITH AN OATH TO SEAT one OF HIS DESCENDANTS UPON HIS THRONE." Acts 2:29-30)

F. Godet in his classic commentary on Romans puts it this way...

Abraham being for the Jews the embodiment of salvation, his case was of capital moment in the solution of the question here treated. This was a conviction which Paul shared with his adversaries. Was the patriarch justified, by faith and by faith alone, his thesis was proved. Was he justified by some work of his own added to his faith, there was an end of Paul's doctrine. In the first part of this chapter, Ro 4:1-12, he proves that Abraham owed his righteousness to his faith, and to his faith alone. In the second Ro 4:13-16, he supports his argument by the fact that the inheritance of the world, promised to the patriarch and his posterity, was conferred on him independently of his observance of the law. The third part, Ro 4:17-22, proves that that very posterity to whom this heritage was to belong was a fruit of faith. In the fourth and last part, Ro 4:23-25, this case is applied to believers of the present. Thus righteousness, inheritance, posterity , everything, Abraham received by faith; and it will be even so with us , if we believe like him." (Godet, Frederick Louis: The Epistle of St Paul to the Romans - Online)

Moule in another classic work on Romans explains why Paul would choose Abraham at this point in his argument, writing that as "father Abraham"...

"...moves across the scene of Genesis, we — even we Gentiles — rise up as it were in reverent homage, honoring this figure at once so real and so near to the ideal...walking with God Himself in a personal intercourse so habitual, so tranquil, so congenial. Is this a name to becloud with the assertion that here, as everywhere, acceptance was hopeless but for the clemency of God “gift-wise, without deeds of law”? Was not at least Abraham accepted because he was morally worthy of acceptance? And if Abraham, then surely, in abstract possibility, others also. There must be a group of men, small or large, there is at least one man, who can “boast” of his peace with God." On the other hand, if with Abraham it was not thus, then the inference is easy to all other men. Who but he is called “the Friend” (2Chronicles 20:7, Isaiah 41:8)? Moses himself, the almost deified Lawgiver, is but “the Servant,” trusted, intimate, honoured in a sublime degree by his eternal Master. But he is never called “the Friend.” That peculiar title seems to preclude altogether the question of a legal acceptance. Who thinks of his friend as one whose relation to him needs to be good in law at all? The friend stands as it were behind law, or above it, in respect of his fellow. He holds a relation implying personal sympathies, identity of interests, contact of thought and will, not an anxious previous settlement of claims, and remission of liabilities. If then the Friend of the Eternal Judge proves, nevertheless, to have needed Justification, and to have received it by the channel not of his personal worth but of the grace of God, there will be little hesitation about other men’s need, and the way by which alone other men shall find it met." (Moule, H C G, Frederick Louis: The Epistle of St Paul to the Romans)
 

David Stern in his "Jewish NT Commentary" comments that

"There can be no doubt that in the 1st century c.e. the doctrine was widespread that descendants can benefit and even can claim salvation on the ground of their ancestors’ righteousness. Yeshua’s opponents made exactly such a claim at (In Jn 8:33 after Jesus had told His audience that if they the truth would set them free, the Jews "answered Him" saying "We are Abraham's offspring, and have never yet been enslaved to anyone; how is it that You say, 'You shall become free'?"), Paul’s own opponents obviously were making use of the idea at [ Paul wrote "Are they Hebrews? So am I. Are they Israelites? So am I. Are they descendants of Abraham? So am I." 2Cor 11:22]. Rabbinic literature does well in pointing up Avraham’s faithful and trusting attitude toward God. For example, the Midrash Rabbah records:
 

“In the 'olam haba [world to come] Israel will sing a new song, as it is said, ‘Sing unto Adonai a new song, for He has done marvelous things’ (Ps98:1). By whose z'khut [merit] will they do so? By the merit of Avraham, because he TRUSTED in the Holy One, blessed be he, as it says, ‘And he TRUSTED in Adonai’ (Ge15:6).” (Exodus Rabbah 23:5)

The present chapter (Romans 4) investigates the nature of Avraham’s own “merit”: what is it that he obtained by his own efforts?... Didn’t he have “works,” meritorious “deeds” that earned him his salvation? This is what Paul’s hypothetical questioner is asking." (Jewish NT Commentary)

THAT ABRAHAM, OUR FOREFATHER ACCORDING TO THE FLESH HAS FOUND: Abraam ton propatora hemon heurekenai (RAN) kata sarka: (Isa 51:2; Mt 3:9; Lk 3:8; 16:24, 25, 29, 30, 31; Jn 8:33,37, 39, 40, 41,53,56; Ac13:26; 2Co11:22) (Ro 4:16; Heb 12:9)

The Jew might remind Paul that Abraham had righteousness and thus the question naturally arises as how did he become righteous? Note Paul's use of the term "our" ("our forefather") which identifies Paul with the Jewish audience.

Forefather (Note Strong's # 4310 is not correct for propater) (propater from pro = before + pater = father) is used only here in the NT and refers to the primary founder of a family, the ancestor, the archetypal founder or the ultimate ancestor.

As discussed above, Paul uses the example of Abraham to prove justification by faith because the Jews held him up as the supreme example of a righteous man. For example in His discussion of discipleship with the Jews who had believed in Him explained...

"I speak the things which I have seen with My Father; therefore you also do the things which you heard from your father." They answered and said to Him, "Abraham is our father." Jesus said to them, "If you are Abraham's children, do the deeds of Abraham." (John 8:38-39)

An accurate understanding of how Abraham received righteousness shows how Judaism's works based righteousness had deviated far from the faith based righteousness.

Paul also would have been very familiar with the rabbinical literature which taught that Abraham was the ultimate example of a man who was justified by works. In the verses that follow, Paul, like a prosecuting attorney, will demonstrate beyond a shadow of a doubt that, to the contrary, the Holy Scriptures clearly teach that Abraham was saved by his faith alone independent of his works.

As translated by the NASB and the NIV (see Vine's note in next paragraph), the phrase "Our forefather according to the flesh" speaks of the physical line of Abraham. The Jews traced their lineage to "father Abraham". God cut  covenant with Abraham in Genesis 15 and again ratified the covenant with Isaac who passed it on to Jacob, whose name was later changed to Israel. Israel had twelve sons who became the fathers of the twelve tribes of Israel. In Paul's day anyone who was born Jewish could trace their lineage through one of the 12 tribes and ultimately back to Abraham. Before his rebirth, Paul was proud of the fact  that he "of the nation of Israel, of the tribe of Benjamin, a Hebrew of Hebrews."  (Php 3:5-note) The typical Jew in Paul's day was proud of their lineage and especially proud that they could trace their bloodline all the way back to "father Abraham".

Vine writes that

The phrase “according to the flesh” can be taken grammatically either with “our forefather” or with “hath found.” Opinions regarding the choice differ. If the latter connection is taken (as does NKJV), the question asks what righteousness Abraham obtained by works, that is, by natural effort and attainment. This is in keeping with what follows in (Ro 4:2). If the phrase is connected with “our forefather,” (as in NASB, NIV) it signifies natural relationship in contrast to the spiritual relationship established by faith, a contrast stressed in (Ro 4:11,12). (Vine, W. Collected writings of W. E. Vine. Nashville: Thomas Nelson )

Considering the aberrant teaching of the rabbis (see examples below) it is not surprising that many of the first century Jews believed they possessed salvation solely on the basis of being Abraham's offspring. In addition, they thought that they determined who was eligible for salvation, because they owned it! Before the coming of Christ, they shared "salvation" (or what they thought was salvation) only with those willing to become Jewish proselytes. When proselytes converted to Judaism, they were instructed to be circumcised and to place under obedience to the Law of Moses. It is surprising to discover that there are many non-Jews today who still feel that in the OT for one to be "saved" they must enter into salvation via Judaism. Nothing could be further from the truth, but this misconception does reflect how good their Jewish "propaganda" has been, even among evangelicals who should know better -- God's righteousness has always been reckoned only on the basis of faith - Sola Fide -- and does not require one to join a particular church or carry out any act (including baptism). Justification is a gift graciously given by God to undeserving sinners.

Jesus became perfect man "according to the flesh" (Ro 1:3-note) that we might be made righteous according to His Spirit.

Found (2147) (heurisko) means to learn the location of something, either by intentional searching or by unexpected discovery learn whereabouts of something. It means to find, discover, come upon, happen to find, to learn something previously not known, frequently involving an element of surprise.

Heurisko is the source of our English word eureka from an exclamation attributed to Archimedes on discovering a method for determining the purity of gold.

Barclay explains Paul's introduction of Abraham remarking that

"Paul begins to speak about Abraham because he was a wise teacher who knew the human mind and the way it works. He has been talking about faith. Now faith is an abstract idea. The ordinary human mind finds abstract ideas very hard to grasp. The wise teacher knows that every idea must become a person, for the only way in which an ordinary person can grasp an abstract idea is to see it in action, embodied in a person. So Paul, in effect, says, "I have been talking about faith. If you want to see what faith is, look at Abraham."

Barclay adds these comments regarding how the Rabbis dealt with Abraham:

"Some few, some very few, of the more advanced Rabbis believed that (that it was purely Avraham's faith which made him a good man in God's sight) There was a rabbinic commentary which said, "Abraham, our father, inherited this world and the world to come solely by the merit of faith whereby he believed in the Lord; for it is said, 'And he believed in the Lord, and he accounted it to him for righteousness.'" Sadly however the great majority of the Rabbis altered the Genesis account of Abraham to match their own beliefs. They held that because Abraham was the only righteous man of his generation, therefore he was chosen to be the ancestor of God's special people. The immediate answer is, "But how could Abraham keep the law when he lived hundreds of years before it was given?" The Rabbis response was an odd theory that Abraham kept the Law by intuition or anticipation. For example we read in the the Apocalypse of Baruch (57:2 ) "At that time, the unwritten law was named among them, and the works of the commandment were then fulfilled." Ecclesiasticus (44:20, 21 ) says that Abraham "kept the law of the Most High and was taken into covenant with God...Therefore God assured him by an oath that the nations should be blessed in his seed." The Rabbis were so attached to their theory of salvation by works that they insisted that it was because of his works that Abraham was chosen, although it meant that they had to argue that he knew the law by anticipation, since it had not yet come! (Barclay, W: The Daily Study Bible Series. The Westminster Press or Logos)

John MacArthur writes that

"In a hypothetical syllogism, Paul says, For if Abraham was justified by works, then he has something to boast about. The major premise is that, if a man could be justified before God by his own human efforts, then he has ground for boasting in himself. The minor premise is that Abraham, as a man, was justified by works. The necessary conclusion would be that Abraham therefore has something to boast about. The major premise is true: If a man could be justified by works, he would indeed have something to boast about, because he would have merited his own salvation. But, as Paul goes on to demonstrate, the minor premise is not true. Consequently, the conclusion is untrue. Abraham did not have anything in himself to boast about before God." (MacArthur, J: Romans 1-8. Chicago: Moody Press or Logos)

One pastor writes:

"If" (1487) (ei) is referred to in Greek as a condition of the first class, which means that what follows is assumed as true. In the present context it is assumed true for the sake of argument (though it is in fact not actually true - now are you confused?).

Wuest's translation may help you see the meaning of the "if"...

"For, assuming that Abraham was justified out of a source of works, he has ground for boasting, but not when facing God."

Justified (1344) (dikaioo [word study] is derived from the noun dike = righteousness) defines the act by which a man is brought into a right state as related to God. Justified means "being declared righteous." Note that verbs which end in –óo generally indicate bringing out that which a person is or that which is desired, but not usually referring to the mode in which the action takes place. 

Dikaioo never means to make anyone righteous or to do away with his violation of the law, by himself bearing the condemnation and the imposed sentence. Abraham or any man in his fallen condition can never do anything in order to pay for his sinfulness and thus be liberated from the sentence of guilt that is upon him as it happens in the world - when a guilty person has paid the penalty of a crime, he is free from condemnation.

In regard to Biblical righteousness, God is the objective standard which determines the content of meaning of dikaios and at the same time keeps that content of meaning constant and unchanging, since He is the unchanging One. Righteousness in the biblical sense is a condition of rightness the standard of which is God, which is estimated according to the divine standard, which shows itself in behavior conformable to God, and has to do above all things with its relation to God, and with the walk before Him.

Paul's statement in this verse ("Abraham was justified by works") may bring to your mind James' question "Was not Abraham our father justified by works, when he offered up Isaac his son on the altar?" This question in Greek expects a "Yes"! So how is this seeming contradiction to be resolved. The point is that Abraham was justified by faith in God's Word, but he then demonstrated that his faith was genuine by his works. The justification by works of which James is speaking is a different "type of justification". James is referring to justification before other people. Stated another way, James is using the word dikaioo or  justified to mean “proved.” We prove to others our genuine faith in Christ through our works. But the justification that comes through faith is before God, and we do not “prove” ourselves to Him by our works (as Paul is explaining in this section of Romans). Instead, God declares us righteous (dikaioo) through our faith in and our association with Christ, the One who died for our sins. Paul has already declared "that a man is justified (declared righteous) by faith apart from works of the Law." (see note Romans 3:28). In summary, Abraham was justified before God by faith but was justified (proved) before men by his works (James 2:21-24).

The rabbis taught a doctrine in which the merits ("works") of Abraham (who they taught had a superfluity of meritorious "credits") would be passed on to the Jews.

HE HAS SOMETHING TO BOAST ABOUT: echei (3SPAI) kauchema: (Ro 3:27; 15:17; Ezek 8:9; Jer 9:23,24; 1Cor 9:16; 2Cor 5:12; 11:12,30; 2Cor 12:1-9; Gal 6:13,14; Eph 2:9)

Boast about (2745) (kauchema noun related to the verb kauchaomai [word study] = to boast <> in turn akin to aucheo = boast + euchomai = express a wish <> in turn from auchen = neck, which vain persons are apt to carry in proud manner) means not the actual boasting itself but the ground of glorying or boasting.

Kauchema is not connected with the word glory (doxa) which is used of God’s glory. It means glory in the sense of exultation or self-congratulation. Kauchema describes the matter or ground of boasting. In this context the ground of Abraham's boasting would have been that he was declared righteous because of his works.

If Abraham’s own works had been the basis of his justification, he would have had every right to boast in God’s presence.

"Justified" by works -- A preacher who had long-departed from the truth of the gospel, told the following story to summarize "the faith" he taught.

It seems that a frog one day fell into a pail of milk, and though he tried every conceivable way to jump out, he always failed. The sides were too high, and because he was floating in the milk he could not get enough leverage for the needed leap. So he did the only thing he could do. He paddled and paddled and paddled some more. And voila! His paddling had churned a pad of butter from which he was able to launch himself to freedom. The preacher’s conclusion was "Just keep paddling, keep on working, keep on doing your best, and you will make it." You may smile at this exaggerated simplification, but this actually describes the "good news" promulgated by many churches and by every non-Christian religion in the world. It is amazingly sad that  “Amazing Grace” is one of the favorite hymns worldwide and yet most of these same people reason that if you just do your best you will somehow make it to Heaven. The truth is that mankind, be he Jew or Gentile, is deeply hostile to the truth of justification by faith alone through God’s grace. Most people are much more comfortable with the motto “We get our salvation the old-fashioned way. We earn it!” This is exactly the falsehood Paul is addressing in this section.
 

As alluded to earlier in this section, among the Jews, Abraham was felt to be the prime example and model of a man who was justified by his works, and this false understanding was amply supported by the rabbinic literature of the day as illustrated below:

For example, the Mishnah’s third division Kiddushin (4.14) makes a specious interpretation of Ge26:5, in which God repeats His covenant promise to Abraham's son Isaac, declaring...

"And I will multiply your descendants as the stars of heaven, and will give your descendants all these lands; and by your descendants all the nations of the earth shall be blessed 5 because Abraham OBEYED Me and KEPT My charge, My commandments, My statutes and My laws."

The Mishnah wrongly concludes
 

“we find that Abraham our father had performed the whole law before it was given, for it is written, ‘Because that Abraham obeyed my voice and kept my charge, my commandments, my statues, and my laws.’

The earlier Book of Jubilees (circa b.c. 100) similarly says,
 

“For Abraham was perfect in all his deeds with the Lord, and well-pleasing in righteousness all the days of his life.”

So perfect was Abraham thought to be that "The Prayer of Manasses" concluded that Abraham had no need of repentance, declaring...
 

“Thou, therefore, O Lord, that art the God of the righteous, hast not appointed repentance unto the righteous, unto Abraham.… ”

Now you can understand why Paul is going to such lengths to refute the preposterous Rabbinical teachings that Abraham performed the whole Law even before it was actually written, that he was perfect in all his deeds, and that he had no need of repentance.

BUT NOT BEFORE GOD: all ou pros ton theon: (Ge 12:12,13,18,20; 20:9, 10, 11, 12, 13; Josh 24:2; 1Cor 1:29; 4:7; Gal 3:22)

"from God's point of view Abraham had no basis at all for pride" (NLT)

How might this truth apply to believers? Many Christians after believing on Christ for their eternal destiny fall back into the trap of spending the rest of their lives trying to gain a sense of God's approval and love by hard, exhausting, committed, dedicated labor. And you can never win God's love that way. You never know when you have done enough. You cannot earn the gift of love, but it is yours if you take it by faith in Christ. And this faith obeys. Not perfectly, but the general direction of this person's life is to live in a such a way so as to please God.

William Newell writes that

"To discover that the greatest saints have no other standing than the weakest saints, is a lesson that is difficult for all of us. So now for the Jew to find that great Abraham has nothing in the flesh, but must be justified by simple faith, like any sinner, is a great shock. There was no honor, no "merit, " in Abraham's believing the faithful God, who cannot lie. The honor was God's. When Abraham believed God, he did the one thing that a man can do without doing anything! God made the statement, the promise; and God undertook to fulfill it. Abraham believed in his heart that God told the truth. There was no effort here. Abraham's faith was not an act, but an attitude. His heart was turned completely away from himself to God and His promise. This left God free to fulfill that promise. Faith was neither a meritorious act by Abraham, nor a change of character or nature, in Abraham: he simply believed God would accomplish what He had promised: "In thee shall all the families of the earth be blessed" (Ge 12:3)." (Newell, William: Romans Verse by Verse) (Bolding added)

A survey by the Barna Research Group suggests widespread confusion about the gospel - even among churchgoers who feel responsible to spread the gospel.

George Barna, president of the Barna Research Group aptly comments that "There is plenty of reason for churches to worry if nearly one-half of their people who believe in evangelism also believe in salvation by works! The central message of Protestantism is in salvation by faith alone in Christ, yet many Protestant evangelizers seem to be preaching a different message.” Respondents from “mainline” Protestant churches tended to believe in salvation by works more frequently than those from “evangelical” churches. Yet pastors from mainline churches seemed more confident in their members’ ability to evangelize. Almost half (46%) of mainline pastors believe their congregations are qualified to present the gospel, while only one-fourth (24%) of Baptist pastors do. 

In another survey in 1992 survey in which one-third of the respondents claimed to be born-again Christians, 54% of all respondents (including so called "born again") stated that all good people will go to heaven whether they have embraced Jesus Christ or not. Furthermore almost 25% of "born again" respondents said that while Jesus was on earth He sinned like other men!

It is still true what G. K. Chesterton said that...

“Merely having an open mind is nothing. The object of opening the mind, as of opening the mouth, is to shut it again on something solid.”

Mark Twain by all accounts was not a believer, and, as the following anecdote suggests, he placed his "faith" in salvation by works. The story is told of a businessman well known for his ruthlessness who announced to Twain that

"Before I die I mean to make a pilgrimage to the Holy Land. I will climb Mount Sinai and read the 10 Commandments aloud at the top."

Twain replied

"I have a better idea. You could stay in Boston and keep them."

Dwight L Moody has this poignant description of salvation apart from works writing that...

"The thief had nails through both hands, so that he could not work; and a nail through each foot, so that he could not run errands for the Lord; he could not lift a hand or a foot toward his salvation, and yet Christ offered him the gift of God; and he took it. Christ threw him a passport, and took him into Paradise."

Would you go to heaven if you died tonight? Do you want to go to heaven? Do you want to know the way? Read the 2 short pamphlets below by D L Moody The Way to God & How to Find It  Heaven: Where It Is, Its Inhabitants & How To Get There

Paul appeals to the Old Testament as a witness testifying that justification has always been by faith not by works.

Scriptures (1124)(see in depth study of graphe) in the plural in the NT describes the Holy Scriptures and in the singular (as in the present verse) it is used to describe a part of it. So more literally Paul is saying "what does the specific passage (Genesis 15:6) say"? Does it make his works the basis of Abraham’s justification? By no means as he goes on to explain here declaring that God Himself, by His own word, has decided this matter.

Paul then personifies the Scripture, in a sense calling this specific passage (Genesis 15:6) to take the stand as a "witness" to corroborate Paul's argument (cf Ro 9:17, 10:11, 11:2, Jn 19:37 James 4:5). Clearly Paul puts much validity in what the Scripture says and he knows the Jews prided themselves on having the Scriptures (Romans 2:17, 18, 19, 20) It is not important what man says about "the way" but only what God says in His Word of Truth. For both Paul and his readers the Scripture was the final and infallible witness.

For example, the Jewish Rabbis often appealed to Biblical citations, sometimes prefacing them with, “What does Scripture say?” Likewise, Jewish teachers often commented on Abraham’s faith as it was described in Genesis 15:6 but in that passage they read it as his “faithfulness” and equate that with one of Abraham's works!

AND ABRAHAM BELIEVED GOD: episteusen (3SAAI) de abraam to theo: (Ge 15:6; Gal 3:6,7, 8; Jas 2:23)

This quotation from Genesis 15:6 is one of the clearest statements in all Scripture about how men can be justified before God. Abraham "trusted" God, and this, rather than his works, was the ground upon which he was accorded "righteousness." Another man was "reckoned righteous" even before Abraham.

Believed (4100) (pisteuo [word study]) as used in the NT to describe saving faith denotes more than mere intellectual assent to a fact. Pisteuo describes an adherence to, a committal to, a  reliance upon or a trust in a person or an object. Thus genuine belief involves not only the consent of the mind, but an act of the heart and will of the subject. Biblical saving faith is not passive assent but an active staking of one's life on the claims of God

The corresponding Hebrew verb ('aman) which is translated "believed" in Genesis 15:6 means “to say amen.” God gave a promise, and Abraham responded “Amen!” It was this faith that was counted for righteousness. Through his faith in God,

“Abraham rejoiced to see My day (he had looked forward to the day of the Messiah, as much of His day as he could understand),” Jesus said, “and he saw it (he "saw" it with eyes of faith) and was glad” (John 8:56).

The Lord Jesus was saying that He was the One to whom Abraham looked forward. Abraham’s faith rested in the coming of Christ.

To paraphrase the respected linguist, W E Vines, saying faith involves

(1) A firm conviction which produces full acknowledgment of God's revelation of Truth,

(2) a personal surrender to the Truth and

(3) a conduct inspired by & consistent with that surrender.

Robert Haldane comments on the quotation from Genesis 15:6 writing that there

...the promise to Abraham is recorded that his seed should be innumerable as the stars of heaven, being the renewal of the promise, Genesis 12:2, when he was called out of his own country. It thus comprehended the truth announced to him at different times, that all the nations of the world should be blessed in his seed, that is, in the Messiah, Galatians 3:16. That promise referred to the one made to our first parents after the fall (Genesis 3:15), in which was included the hope of redemption to be accomplished by the Deliverer of mankind, Who was to spring from him, as God declared to Abraham." (Haldane, R: An Exposition of Romans)

Like Paul, who wrote this epistle to Rome, Abraham was sovereignly and directly chosen by God. Neither Abraham nor Paul was searching for God when they were divinely called and commissioned. Abraham had probably never heard of the true God, whereas Paul knew a great deal about Him. Abraham was seemingly content with his idolatrous paganism, and Paul was content with his traditional, but false, Judaism. When God called Abraham, or Abram (his original name) He gave no reason for selecting that pagan from the millions of others in the world. Nowhere in Scripture is the reason given. God chose Abraham because that was His divine will, which needs no justification or explanation.

FAITH:
Not the Ground
but
The Channel

Abraham was a man of faith but his faith was not a meritorious work. His faith was not the ground of justification but it was simply the channel through which it is received and it, too, is a gift (Ep2:8 2Pe1:1). by grace you have been saved through faith; and that not of yourselves, it is the gift of God;

Kenneth Wuest explains Abraham's act of faith writing that...

"It was the act of Abraham placing himself in such an attitude of trust in and acceptance of God’s blessings that made it possible for God to bestow righteousness upon him. It is like the proffered hand of a drowning man that makes it possible for the life guard to save him. There is nothing meritorious in the act of a drowning man in stretching out his hand in order to be saved. It is the efficient medium through which he is saved. Thus, the act of faith on the sinner’s part is not meritorious but only the efficient medium through which God is able save him. The “it” therefore refers to the outstretched hand of faith of a sinner reaching out for salvation that God grasps in His own to lift him out of the mire of sin and place him upon the Rock, Christ Jesus." (Wuest, K. S. Wuest's Word Studies from the Greek New Testament: Studies in the Vocabulary of the Greek New Testament: Grand Rapids: Eerdmans)

AND IT (his faith = the instrument) WAS RECKONED (imputed) TO HIM AS RIGHTEOUSNESS: kai elogisthe (3SAPI) auto eis dikaiosunen: (Ro 4:5,9,11,22, 23, 24, 25; Ps 106:31)

Reckoned (3049)  (logizomai from lógos = reason, word, account) (Click for in study of logizomai)  means to take something that belongs to someone else and credit it to another’s account. 

Logizomai - 40x in 39v - Luke 22:37; John 11:50; Acts 19:27; Rom 2:3, 26; 3:28; 4:3ff, 8ff, 22ff; 6:11; 8:18, 36; 9:8; 14:14; 1 Cor 4:1; 13:5, 11; 2 Cor 3:5; 5:19; 10:2, 7, 11; 11:5; 12:6; Gal 3:6; Phil 3:13; 4:8; 2 Tim 4:16; Heb 11:19; Jas 2:23; 1 Pet 5:12. NAS = consider(6), considered(2), counted(1), counting(1), credit(1), credited(9), credits(1), dwell(1), maintain(1), numbered(2), propose(1), reason(1), reckoned(2), regard(4), regarded(3), suppose(1), take into account(3), thinks(1).

Logizomai was a secular bookkeeping term which meant to make an entry in the account book or to put to one's account. It carried the economic and legal meaning of crediting something to another’s account. It means to calculate or reckon, as when figuring an entry in a ledger. The purpose of the entry is to make a permanent record that can be consulted whenever needed. It means to credit money to a particular account. It means that when you deposit $1000, the bank credits your account with $1000. Therefore when you write a check for $500, you don't worry about it because you are reckoning on the fact that money is actually in your account. The purpose of the entry was to make a permanent record that can be consulted whenever needed.

Abraham believed God, and his act of faith was placed to his account in value as righteousness.

He believed God and his act of faith was credited to him for righteousness.

He believed God and his act of faith was computed as to its value, and there was placed to his account, righteousness.

Note that Abraham’s act of faith was not looked upon as a meritorious work deserving a reward. What his faith did do was provide a channel through which God worked His redeeming grace. Faith is a convicted heart reaching out to receive God’s free and unmerited gift of salvation.

Logizomai was used in early secular documents as follows...

•   “put to one’s account,"
•   "let my revenues be placed on deposit at the storehouse"
•   "I now give orders generally with regard to all payments actually made or credited to the government.”

NKJV "just as David also describes the blessedness of the man to whom God imputes righteousness apart from works"

Reckoning (crediting, imputing) is essentially a one-sided transaction. In other words Abraham did nothing meritorious to warrant Christ's righteousness. God credited it to him when he believed. God took Christ's righteousness and credited it to Abraham and this transaction occurred because Abraham believed God and His promises in Genesis 15:6. Paul is using Abraham to illustrate that when he trusted God, his moral and spiritual "books" were balanced so to speak and that it was not because of something Abraham did or did not do.

John MacArthur writes that...

"Even though Abraham’s repeated disobedience was sinful and brought harm to himself and others, God even used that disobedience to glorify Himself. Those acts of disobedience testify that, contrary to rabbinical teaching, Abraham was sovereignly chosen by God for His own divine reasons and purposes, not because of Abraham’s faithfulness or righteousness. Abraham was chosen by God’s sovereign, elective grace, not because of his works or even because of his faith. His faith was acceptable to God only because God graciously reckoned, or counted, it as righteousness. It was not the greatness of Abraham’s faith that saved him but the greatness of the gracious Lord in whom he placed his faith. Faith is never the basis or the reason for justification, but only the channel through which God works His redeeming grace. Faith is simply a convicted heart reaching out to receive God’s free and unmerited gift of salvation. (MacArthur, J: Romans 1-8. Chicago: Moody Press)

Righteousness (1343) (dikaiosune [word study] from dikaios [word study] = being proper or right in the sense of being fully justified being or in accordance with what God requires) is the quality of being upright. In its simplest sense dikaiosune conveys the idea of conformity to a standard or norm. In this sense righteousness is the opposite of hamartia (sin), which is defined as missing of the mark set by God. In this sense righteousness is the opposite of hamartia (sin), which is defined as missing of the mark set by God.

Dikaiosune is rightness of character before God and rightness of actions before men.  Righteousness of God could be succinctly stated as all that God is, all that He commands, all that He demands, all that He approves, all that He provides through faith in Christ (Click here to read Pastor Ray Pritchard's interesting analysis of righteousness in the Gospel of Matthew).

As sinners, we have no righteousness that would be acceptable to God

"For all of us have become like one who is unclean, And all our righteous deeds are like a filthy garment" (Isaiah 64:6)

But God has given His Word of promise. When we respond to Him in faith, against our name in His account book He makes an entry that says in effect,

’This person is righteous in My sight!’

Our faith has been credited to us as righteousness. Some might complain that this concept of salvation is too crude. But that same person, if he went to his bank and found that someone had credited his account with the gift of $10 million, wouldn’t complain about “crude.” He would more likely shout for joy! In Christ, God has credited to us something far more precious than worldly wealth.

Kenneth Wuest explains how Abraham could possess Christ's righteousness before Christ was made sin in His place...

"God put to Abraham’s account, placed on deposit for him, credited to him, righteousness. The actual payment had not been made, the actual bestowal of righteousness had not been consummated, and for the reason that our Lord had not yet paid the penalty of man’s sin and had not yet been raised from the dead. Abraham possessed righteousness in the same manner as a person would possess a sum of money placed in his account in a bank. Since the resurrection, Old Testament saints share with New Testament believers the possession of Christ as the righteousness in which they stand, guiltless and righteous for time and for eternity." (Wuest, K. S. Wuest's Word Studies from the Greek New Testament: Studies in the Vocabulary of the Greek New Testament: Grand Rapids: Eerdmans)