BUT IF YOU BEAR THE NAME JEW: Ei de su Ioudaios eponomaze (2SPPI): (Ro 2:28,29; 9:4-7; Ps 135:4; Isa 48:1,2; Mt 3:9; 8:11,12; Jn 8:33; 2Co 11:22; Gal 2:15; Eph 2:11; Phil 3:3-7; Rev 2:9; 3:1,9) (See Naves Topics Formalism; Hypocrisy; Self-Righteousness Torrey's Topic Hypocrites)

"If" (ei) is what is referred to as a "first class conditional" statement and signifies that what follows is assumed to be true. It can often be translated with the word "Since" ("Since you bear the name Jew" which they did indeed bear)

Bear (2028) (eponomazo from epí = upon + onomázo = to name) means to  call, to classify oneself by means of a name, title, or attribution.

Every "boast" of the Jew in this passage concerns the possession of law; although the Jew should gratefully receive the law as a gift from God, Paul will show how mere possession of the law justifies no one. The indictment of the Jew comes down to this principle: "You have the law, do you keep it? You can see how others break the law, do you see how you break it also?" Remember that much of rabbinic Judaism of Paul’s day interpreted the law in such a way that one might consider themselves completely justified by the law; yet Jesus exposed the error of such interpretations. (see discussion by Jesus beginning in Matthew 5:19-20 commentary notes) We only want to apply God’s law to our actions; God also applies His law to our attitudes.

Jew (2453) (Ioudaios)

Hebrew distinguishes a Hebrew-speaking Jew from a Greek-speaking one.

Jew distinguishes a Jew from a Gentile, and denotes nationality.

Israelite is the most august title of all, speaking of the fact that the Jew is a member of the theocracy, and thus an heir of the promises (Trench).

Previously called Hebrews and Israelites, by the first century “Jew” had become the most common name for the descendants of Abraham through Isaac. “Jew” is from “Judah,” (“praise”), one of the 12 tribes and the designation for the southern half of Solomon’s kingdom after his death. From the time of the Babylonian captivity, the whole race bore this title. Their great heritage, however, (cf. Ge 12:3) became a source of pride and complacency (cf. Jon 4:2; Mic 3:11, 12; Mt 3:7-9; John 8:31-34, 40-59), which led to judgment instead of “praise.” He could and should have become a "guide" and "light" to those in darkness (v19). So Paul is showing the self-righteous Jews, boasting in their status as God's chosen people, that just being a Jew is not sufficient for salvation.

The ISBE entry notes that

"Jew" denotes originally an inhabitant of Judah (2 Kings 16:6 applies to the two tribes of the Southern Kingdom), but later the meaning was extended to embrace all descendants of Abraham. In the Old Testament the word occurs a few times in the singular. (Esther 2:5; 3:4, etc.; Jeremiah 34:9; Zechariah 8:23); very frequently in the plural in Ezra and Nehemiah, Esther, and in Jeremiah and Daniel. The adjective in the Old Testament applies only to the "Jews' language" or speech (2 Kings 18:26,28 parallel Nehemiah 13:24; Isaiah 36:11,13). "Jews" (always plural) is the familiar term for Israelites in the Gospels (especially in John), Acts, Epistles, etc. "Jewess" occurs in 1 Chronicles 4:18; Acts 16:1; 24:24. In Titus 1:14 note a warning is given against "Jewish fables" (in Greek the adjective is found also in Galatians 2:14). The "Jews' religion" (Ioudaismos) is referred to in Galatians 1:13,14. (James Orr)

AND RELY UPON THE LAW: kai epanapaue (2SPMI) nomo (23; Ro 9:4,32; Jer 7:4-10; Zep 3:11; Lu 10:28; Jn 5:45; 7:19; 9:28,29)(cp only "doers...justified" v13)

Rely (1879) (epanapauomai from epí = upon + anapaúomai = to rest <> from aná = again + paúo = cease, give rest) (Used here and Luke 10:16 "And if a man of peace is there, your peace will rest upon him; but if not, it will return to you.") conveys the basic meaning of to rest on. The idea is to refresh oneself back upon anything.  It describes finding "comfort" through confident dependence on something, trust in and in context trusting in the Law but not being doers of it, which pictures a blind and mechanical reliance on the Mosaic law.

It means to continue, remain with the sense of remaining upon. In the OT (LXX), this word is describes the Spirit of God "resting" on men (Nu 11:25-16) So here the picture Paul paints is of a spiritually blind mechanical "resting upon" or relying upon the Mosaic Law. The present tense of this verb pictures this as their continual attitude. Paul says that you continually (present tense) rest upon with a blind and mechanical reliance on the Mosaic law.

From (Ro 2:17-29) God shows that His judgment is based on reality not religious profession.

Epanapauomai is used 8 times in the (Nu 11:25, Nu 11:26, 2 Ki. 2:15, 2 Ki. 5:18, 2 Ki. 7:2, 2 Ki. 7:17, Ezek. 29:7, Mic. 3:11) in some cases meaning literally "leaning upon" and in others describing the Spirit "resting upon" men Moses recording for example...

Then the LORD came down in the cloud and spoke to him; and He took of the Spirit who was upon him and placed Him upon the seventy elders. And it came about that when the Spirit rested upon them, they prophesied. But they did not do it again. 26 But two men had remained in the camp; the name of one was Eldad and the name of the other Medad. And the Spirit rested upon them (now they were among those who had been registered, but had not gone out to the tent), and they prophesied in the camp. (Nu 11:25-26)

AND BOAST IN GOD: kai kauchasai (2SPMI) en theo: (Is 45:25; 48:2; Mic 3:11; Jn 8:41) (Ro 2:23 3:27 4:2 contrast real "boasting" Ro 15:17 & real praise 2:29):

NIV = "brag about your relationship to God"

Boast (2744) (kauchaomai akin to aucheo = boast + euchomai = pray to God <> auchen = neck which vain persons are apt to carry in proud manner) means to boast over a privilege or possession. It is used in the OT of any proud and exulting joy and is expressive of triumphant, rejoicing confidence in God. This word combines ideas of jubilation and confidence into one word to describe "joyful confidence".

The Jew continually (present tense) boasted in God as the covenant God of Israel and that they were His peculiar people. Jesus corrected their faulty misconception that God was their Father accusing the Jews (who paradoxically had believed in Him in John 8:30-31 indicating that their belief was only a profession or mental/intellectual assent and not a changed/circumcised heart!) declaring ...

"You are doing the deeds of your father." They said to Him, "We were not born of fornication; we have one Father, even God." Jesus said to them, "If God were your Father, you would love Me; for I proceeded forth and have come from God, for I have not even come on My own initiative, but He sent Me. "Why do you not understand what I am saying? It is because you cannot hear My word. "You are of your father the devil, and you want to do the desires of your father. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. Whenever he speaks a lie, he speaks from his own nature; for he is a liar, and the father of lies. (John 8:41-44)

Even a Divinely revealed religion provides no security to its professor if it is devoid of reality. It makes no difference whether it is the "Jews’ religion" at the beginning of their existence as a nation or Christianity today. Profession does not always signify possession!

In the above verses Paul is directly addressing the Jew. He shows that the Jew "rested" on The Law, —on having it; and were proud that the will of the true God had been revealed to them, that they "knew" that will, and were therefore able to "approve the things that: are excellent." The Jews developed a false confidence in themselves as guides, lights,  correctors of the foolish, teachers, because they felt (self deception) that in the law they had "the form of knowledge and of the truth." Their problem was that they did not apply the Law to themselves -- their teaching, preaching, saying what folks should be, abhorring idols, glorying in The Law! The result was that the very Name they boasted in was blasphemed among the Gentiles because of their blatant selfishness, pride, covetousness, and general wickedness!

William Newell applies Paul's truths to "Christians" writing that...

"If we should thus apply this passage (Romans 17-29), must it not read something like this?—

"If you bear the name of a Christian, and rest on having the gospel, and glory God, and know His will, and approve the things that are excellent, being instructed out of the gospel; and are confident that you yourself are a guide of the blind, having in the gospel the form of knowledge and of the truth"

— Then would follow the searching questions of Romans 2:21-22; for do we not know teachers that teach others, but refuse to follow their own teaching? And preachers that denounce stealing, but are accused by the world of being themselves money-grabbers? So it would read,

AND KNOW HIS WILL AND APPROVE THE THINGS THAT ARE ESSENTIAL: kai ginoskeis (2SPAI) to thelema kai dokimazeis (2SPAI) ta diapheronta (PAPNPA): (Dt 4:8; Ne 9:13,14; Ps 147:19,20; Lu 12:47; Jn 13:17; 1Co 8:1,2; Js 4:17) (approve Phil 1:10; 1 Th 5:21; Heb 5:14)

Know (1097) (ginosko) (present tense) means taking in knowledge in regard to something or someone, knowledge that goes beyond the merely factual, thus Wuest translates it "have an experiential knowledge". By extension, the term frequently was used of a special relationship between the person who knows and the object of the knowledge. For example, ginosko, was often used of the intimate relationship between husband and wife and between God and His people.

Will (2307) (thelema from thelo = to will) means what one wishes or has determined shall be done or that which is desired or wished for. It refers to a desire which proceeds from one’s heart or emotions. This term expresses the result of one’s purpose or desire. Thelema has both an objective meaning (“what one wishes to happen”) and a subjective connotation (“the act of willing or desiring”). The word conveys the idea of desire, even a heart’s desire, for the word primarily expresses emotion instead of volition. Thus God’s will is not so much God’s intention, as it is His heart’s desire, His gracious disposition. It refers to His will not as a demand but an inclination of pleasure towards that which is liked, which pleases and creates joy. God’s will signifies His gracious disposition toward something or what God Himself does of His own good pleasure.

Approve (1381) (dokimazo from dokimos = tested, proved or approved, tried as metals by fire and thus purified from dechomai = to accept, receive) (Click for in depth study of dokimazo) means  means to assay, to test, to prove, to put to the test, to make a trial of, to verify, to discern to approve.

Paul is saying "You Jews...

"after (continually = present tense) having put to the test for the purpose of approving the things that differ (essential), and having found that they meet your specifications, you put your approval upon them." (Wuest)

Dokimazo involves not only testing but determining the genuineness or value of an event or object. That which has been tested is demonstrated to be genuine and trustworthy.

Essential (1308) (diaphero from dia = transition or separation + phéro = carry, bear) means literally to carry two ways and so to carry different ways and then comes to mean "to differ”. As used in this verse (and in Philippians 1:10) diaphero (ta diapheronta) refers to "the things different" and thus has the meaning of distinguishing things that are different.

Diaphero  is used of those moral and spiritual concepts and actions which involve delicate and keen distinctions, those that require a deep and keen discernment to recognize. Not the ordinary, everyday, easily understood spiritual obligations, but the finer points of the Law. It speaks of those things that are superior, vital, that surpass, that excel!

Vincent comments that diaphero...

may also mean the things which differ; in which case we shall render provest instead of approvest. The sense will then be: thou dost test with nice discrimination questions of casuistry. Compare Philip. 1:10. The latter interpretation seems preferable, being borne out by the succeeding being instructed.

BEING INSTRUCTED OUT OF THE LAW: katechoumenos (PPPMSN) ek tou nomou: (see notes Romans 15:4; Ps 19:8; 119:98-100,104,105,130; Pr 6:23; see notes 2 Timothy 3:14-15; 2 Timothy 3:16-17)

Instructed (2727) (katecheo from katá = down or intensive + echeo = sound, our English "echo") (see related word sounded forth = execheo) means to literally to sound down on or into the ears. From this the derived meaning is “to inform” or “to instruct orally.” The idea is to re-sound, to re-echo, to teach by by insistent repetition into the ears as the Arabs do when learning the Koran (learning aloud). The present tense indicates they were continuously being (passive voice) instructed out of the Law.  Continuously systematically instructed through catechetical and synagogue instruction. This formal instruction is the basis of the critical discrimination or discernment.

Katecheo is used 8 times in the NAS (Luke; Acts 3x; Romans; 1 Corinthians; Galatians) and is translated instruct, 1; instructed, 2; taught, 2; teaches, 1; told, 2; .

The idea is to teach by word of mouth, to teach in systematic or detailed manner, to indoctrinate ("catechize"). To drill a teaching into another which as alluded to can imply learning by repetition.

Luke wrote his Gospel so that Theophilus might know the certainty of those things concerning which he had been informed orally or catechized (Luke 1:4).

so that you might know the exact truth about the things you have been taught (katecheo) (Luke 1:4)

 Apollos was catechized or orally informed, Luke writing that he...

had been instructed (katecheo) in the way of the Lord; and being fervent in spirit, he was speaking and teaching accurately the things concerning Jesus, being acquainted only with the baptism of John (Acts 18:25)

The Jews had been orally informed by Paul in (Acts 21:21, 24)

As used here in Romans 2:18, Paul says that the Jews were taught orally out of the law.

Paul preferred to speak five understandable words than ten thousand words in another language, so that he could then orally teach others

"however, in the church I desire to speak five words with my mind, that I may instruct others also, rather than ten thousand words in a tongue." (1Cor. 14:19)

God commands that the person who has been orally informed about His Word should share with him who orally teaches

And let the one who is taught the word share all good things with him who teaches. (Gal. 6:6).

In summary, teaching involves the oral passing on of information about the things of God. It is catechizing, informing by word of mouth.

Katecheo is the source of our English word “catechism” - those doing the teaching were called catechists and those receiving it were called catechumens.

AND ARE CONFIDENT THAT YOU YOURSELF: pepoithas (2SRAI) te seauton: (Pr 26:12; Isa 5:21; 56:10; Matthew 6:23 note; 15:14; 23:16-26; Mk 10:15; Jn 7:46-49; 9:34,40,41; 1Co 3:18; 4:10; 8:1,2; Rev 3:17,18)

Confident (3982) (peitho) means literally “are persuaded". Peitho is a strong verb, carrying the components of confidence, reliance, and hope. The perfect tense  means to cause to come to a particular point of view or course of action. The idea is to come to a settled persuasion concerning something or to be persuaded. It means to be so convinced that one puts confidence in something or someone.

This verb suggests that what follows is the result of an idea not only of superiority but of self-complacency. Because they possessed the law, the Jews were confident that they were spiritually superior teachers: guides to blind pagans (cf. Mt 23:24-28), light (cf. Isa 42:6), wise in God’s ways, and able to teach babes (probably a reference to Gentile proselytes to Judaism).

ARE A GUIDE TO THE BLIND: hodegon einai (PAN) tuphlon:

Guide (3595) (hodegos from hodos = way + hegeomai = lead) is literally "a leader on the way", a conductor, a guide, a leader.

Hodegos is used 5 times in the NT (Matthew 3x; Acts; Romans) (only once in the LXX - Ezra 8:1) and translated as guide or leader (KJV).

The NT uses it metaphorically of a teacher as in this verse and by Jesus three times in Matthew...

"Let them (the Pharisees) alone; they are blind guides of the blind. And if a blind man guides a blind man, both will fall into a pit." (Mt 15:14)

A T Robertson in his "Word Pictures" notes that this is a "Graphic picture. Once in Cincinnati a blind man introduced me to his blind friend. He said that he was showing him the city. Jesus is not afraid of the Pharisees. Let them alone to do their worst. Blind leaders and blind victims will land in the ditch. A proverbial expression in the OT."

"Woe to you (hypocritical Scribes and Pharisees), blind guides, who say, 'Whoever swears by the temple, that is nothing; but whoever swears by the gold of the temple, he is obligated.' ... 24 "You blind guides, who strain out a gnat and swallow a camel!" (Mt 23:16, 24)

The last use of hodegos refers to Jesus' betrayer Judas, Luke recording Peter's assessment...

"Brethren, the Scripture had to be fulfilled, which the Holy Spirit foretold by the mouth of David concerning Judas, who became a guide to those who arrested Jesus. (Acts 1:16)

Blind (5185) (tuphlos from tuphlóo = envelop with smoke, be unable to see clearly) referred to literal blindness (Mt 9:27, 28; 11:5; 12:22; Lu 7:21, 22; Jn 9:1ff.; Acts 13:11 Lev 19:14; Job 29:15) or more often to spiritual blindness. Figuratively tuphlos picture one's mind as blind, ignorant, stupid, slow of understanding, being unable to understand, incapable of comprehending (see Mt 15:14; 23:16, 17, 19, 24, 26; Lu 4:18; Jn 9:39,40,41; Ro 2:19; 2Pe 1:9; Rev 3:17; Isa 42:16,18,19; 43:8)

Tuphlos is used 50 times in the NAS (Matthew 14x; Mark 5x; Luke 7x; John 16x; Acts; Romans; 2 Peter; Revelation).

Jesus called the hypocritical religious leaders of His day "blind guides" or “wayleaders”, blind because instead of leading the people to the Light of the world and eternal life, the were leading the people who were in temporal (spiritual) darkness to eternal darkness. Jews in general, and the scribes and Pharisees in particular, considered themselves to be superior mentors of the community in spiritual and moral matters. They saw themselves as religious guides to their unlearned Jewish brethren and especially to the spiritually blind Gentile pagans. But because of their arrogant pride and blatant hypocrisy, Jesus charged them with “blindness” in regard to "the Way, the Truth and the Life"! Far from being qualified to guide others, they were themselves in desperate need of the "Way Leader", Christ Jesus.

A LIGHT TO THOSE WHO ARE IN DARKNESS: phos ton en skotei:  (Isa 49:6,9,10; Mt 4:16; Matthew 5:14 note; Lu 1:79; Acts 26:18; Philippians 2:15 note)

Light (5457) (phos) can refer to literal light (Lu 8:16; Jn 11:9) but more often in the NT has a figurative meaning. Light is closely associated with God (1Jn 1:7) Who “is light” (1Jn 1:5). John uses light symbolism to cast Jesus in the divine light and to show His oneness with the One who sent Him (1Jn 1:4-9; John 8:12; 9:5; 12:46; cf. Lu 2:32). Those who are enlightened with the truth (believers) are called “children of light” (Eph 5:8; cf. Lu 16:8; Jn 12:36; 1Th 5:5). This symbolic use of light explains the emphasis on the eyes as the organs of perception (e.g., Lu 11:34-36), the close association of “seeing” with “believing,” and the antipathy toward darkness throughout the NT.

Matthew quotes Isaiah 9:2...

"THE PEOPLE WHO WERE SITTING IN DARKNESS (skotos) SAW A GREAT LIGHT (phos = Messiah) AND TO THOSE WHO WERE SITTING IN THE LAND AND SHADOW OF DEATH, UPON THEM A LIGHT (phos = Messiah) DAWNED." (Mt 4:16)

Darkness (4655) (skotos from skia = shadow  thrown by an object. Skia it can assume the meaning of skotos and indicate the sphere of darkness) is literally that sphere in which light is absent.) (Click in depth study of skotos) can refer to literal or spiritual darkness in the NT.

Skotos is used figuratively here to refer to spiritual or moral darkness (including a lack of understanding)

Luke records that Jesus was...

TO SHINE UPON THOSE WHO SIT IN DARKNESS (skotos) AND THE SHADOW OF DEATH, to guide our feet into the way of peace." (Lu 1:79)

The nation of Israel, was called out from all the nations to be a light to the Gentiles, a role they, for the most part failed to fulfill in the OT, but which Jesus perfectly fulfilled, Isaiah recording the prophecy...

"I am the LORD, I have called You (Messiah) in righteousness, I will also hold You by the hand and watch over You, and I will appoint You as a covenant to the people, As a light to the nations (Simeon saw the beginning of this fulfillment at Christ’s first coming in Luke 2:32) (Isaiah 42:6)

And again Isaiah speaks prophetically of Messiah...