Agape love is the love of choice, the love of serving with humility, the highest kind of love, the noblest kind of devotion, the love of the will (intentional, a conscious choice) which is not motivated by superficial appearance, emotional attraction, or sentimental relationship. Agape is not based on  pleasant emotions or good feelings that might result from a physical attraction or a familial bond. Agape chooses as an act of self-sacrifice to serve the recipient. From all of the descriptions of agape love, it is clear that true agape love is a sure mark of salvation and in fact is impossible to carry out unless one is genuinely borne again.

Agape love does not depend on the world’s criteria for "love". Nevertheless, believers can fall into the trap of blindly following the world’s demand that a lover feel positive toward the beloved. This is not agape love, but is a love based on impulse. Impulsive love characterizes the spouse who announces to the other spouse that they are planning to divorce their mate. Why? They reason “I can’t help it. I fell in love with another person!” Christians must understand that this type of impulsive love is completely contrary to God’s decisive love, which is decisive because He is in control and has a purpose in mind. There are many reasons a proper understanding of the truth of God's word (and of the world's lie) is critical and one of the foremost is Jesus' declaration that

By this all men will know that you are My disciples, if you have love (agape) for one another. (John 13:35). (Comment: Agape is the badge of discipleship and the landmark of heaven! (Jn 13:35). )

Agape in the Greek classics spoke of a love called out of one’s heart by the preciousness of the object loved. This is the idea inherent in the Father's proclamation "This is My beloved Son..." Agape is the love that was shown at Calvary. Thus agape is God’s love, and is the love that God is. It is not human affection but is a divine love, commanded by God, produced as fruit in the heart of a surrendered saint by the Holy Spirit (God Who is at work in us to will and to work to His good pleasure) (see note Romans 5:5; Gal 5:22), self-sacrificial in nature seeking the benefit of the one who is loved, a love which means death to self and defeat for sin since the essence of sin is self-will and self-gratification, a love activated by personal choice of our will (working out our salvation in fear and trembling) not based on our feelings toward the object of our love and manifested by specific actions as described in this section of 1Corinthians 13:4-7 where we see "love in action". 

Agape may involve emotion, but it  must always involve action. Agape is unrestricted, unrestrained, and unconditional. Agape love is the virtue that surpasses all others and in fact is the prerequisite for all the others. Jesus when asked

Teacher, which is the great commandment in the Law?” replied ”You shall love (agapao - related verb) the Lord your God with all your heart, and with all your soul, and with all your mind.’ “This is the great and foremost commandment." (Mt 22:36-38)

 John MacArthur explains that

Agape love is the greatest virtue of the Christian life. Yet that type of love was rare in pagan Greek literature. That’s because the traits agape portrays—unselfishness, self-giving, willful devotion, concern for the welfare of others—were mostly disdained in ancient Greek culture as signs of weakness. However, the New Testament declares agape to be the character trait around which all others revolve. The apostle John writes, “God is love, and the one who abides in love abides in God, and God abides in him” (1 John 4:16). (MacArthur, J. The Power of Integrity : Building a Life Without Compromise, page 133. Wheaton, Ill.: Crossway Books) (Bolding added)

F B Meyer wrote the following regarding agape love...

Wherever there is true love, there must be giving, and giving to the point of sacrifice. Love is not satisfied with giving trinkets; it must give at the cost of sacrifice: it must give blood, life, all. And it was so with the love of God. "He so loved the world, that He gave his only-begotten Son." "Christ also loved and gave Himself up, an offering and a sacrifice to God." (See note Ephesians 5:2)

We are to imitate God's love in Christ. The love that gives, that counts no cost too great, and, in sacrificing itself for others, offers all to God, and does all for His sake. Such was the love of Jesus--sweet to God, as the scent of fields of new-mown grass in June; and this must be our model.

Not to those who love us, but who hate; not to those who are pleasant and agreeable, but who repel; not because our natural feelings are excited, but because we will to minister, even to the point of the cross, must our love go out. And every time we thus sacrifice ourselves to another for the sake of the love of God, we enter into some of the meaning of the sacrifice of Calvary, and there is wafted up to God the odour of a sweet smell.  (Devotional Commentary on Ephesians)

Kenneth Wuest describes agape love noting that...

Agape is a love that impels one to sacrifice one’s self for the benefit of the object loved...(it) speaks of a love which is awakened by a sense of value in the object loved, an apprehension of its preciousness.

Wuest explains that phileo love is "an unimpassioned love, a friendly love. It is a love that is called out of one’s heart as a response to the pleasure one takes in a person or object. It is based upon an inner community between the person loving and the person or object loved. That is, both have things in common with one another. The one loving finds a reflection of his own nature in the person or thing loved. It is a love of liking, an affection for someone or something that is the outgoing of one’s heart in delight to that which affords pleasure. The Greeks made much of friendship, and this word was used by them to designate this form of mutual attraction."..."We gather, therefore, that agape is a love of devotion (Ed note: and volition), while phileō is a love of emotion. There is another distinction we must be careful to note, and that is that agape is love that has ethical qualities about it, obligations, responsibilities, where phileō is a non-ethical love, making no ethical demands upon the person loving.

In contrasting phileo and agape love, we might say that the former is a love of pleasure, the latter a love of preciousness; the former a love of delight, the latter a love of esteem; the former a love called out of the heart by the apprehension of pleasurable qualities in the object loved, the latter a love called out of the heart by the apprehension of valuable qualities in the object loved; the former takes pleasure in, the latter ascribes value to; the former is a love of liking, the latter a love of prizing.

(Agape is) a love that denies self for the benefit of the object loved.

(Agape describes the)  love of the Spirit-filled husband, purified and made heavenly in character.

(Agape is)  the love which the Holy Spirit sheds abroad in the heart of the yielded believer  (see note Romans 5:5)

The saint is to order his behavior or manner of life within the sphere of this divine, supernatural (agape) love produced in his heart by the Holy Spirit. When this love becomes the deciding factor in his choices and the motivating power in his actions, he will be walking in love. He will be exemplifying in his life the self-sacrificial love shown at Calvary and the Christian graces mentioned in 1Co 13:4-8." (It is) a love that is willing to sacrifice one’s self for the benefit of that brother, a love that causes one to be long suffering toward him, a love that makes one treat him kindly, a love that so causes one to rejoice in the welfare of another that there is no room for envy in the heart, a love that is not jealous, a love that keeps one from boasting of one’s self, a love that keeps one from bearing one’s self in a lofty manner, a love that keeps one from acting unbecomingly, a love that keeps one from seeking one’s own rights, a love that keeps one from becoming angry, a love that does not impute evil, a love that does not rejoice in iniquity but in the truth, a love that bears up against all things, believes all things, hopes all things, endures all things. That is the kind of love which God says one Christian should have for another."

(Agape love) speaks of a love which is awakened by a sense of value in an object which causes one to prize it. It springs from an apprehension of the preciousness of an object. It is a love of esteem and approbation. The quality of this love is determined by the character of the one who loves, and that of the object loved. (In Jn 3:16) God’s love for a sinful and lost race springs from His heart in response to the high value He places upon each human soul. Every sinner is exceedingly precious in His sight. “Phileo” which is another word for love, a love which is the response of the human spirit to what appeals to it as pleasurable, will not do here, for there is nothing in a lost sinner that the heart of God can find pleasure in, but on the contrary, everything that His holiness rebels against. But each sinner is most precious to God, first, because he bears the image of his Creator even though that image be marred by sin, and second, because through redemption, that sinner can be conformed into the very image of God’s dear Son. This preciousness of each member of the human race to the heart of God is the constituent element of the love that gave His Son to die on the Cross. The degree of the preciousness is measured by the infinite sacrifice which God made. The love in Jn 3:16 therefore is a love whose essence is that of self-sacrifice for the benefit of the one loved, this love based upon an evaluation of the preciousness of the one loved. (Wuest, K. S. Wuest's Word Studies from the Greek New Testament: Eerdmans)  (Bolding added)

John MacArthur has numerous excellent comments regarding agape love...

We have no capacity to generate (agape love) on our own. The Greek word for that kind of love is agape, and it is characterized by humility, obedience to God, and self-sacrifice. (MacArthur, J. Drawing near: August 3. 2002. Wheaton, Ill.: Crossway Books)

Biblical agapē love is not an emotion but a disposition of the heart to seek the welfare and meet the needs of others. “Greater love has no one than this, that one lay down his life for his friends,” Jesus said (John 15:13). And that is exactly what Jesus Himself did on behalf of those God has chosen to be saved. In the ultimate divine act of love, God determined before the foundation of the earth that He would give His only Son to save us." (MacArthur, J: Ephesians. 1986. Chicago: Moody Press)

(Agape) Love is an attitude of selflessness. Biblical agape love is a matter of the will and not a matter of feeling or emotion, though deep feelings and emotions almost always accompany love. God’s loving the world was not a matter simply of feeling; it resulted in His sending His only Son to redeem the world (Jn 3:16). Love is self-less giving, always self-less and always giving. It is the very nature and substance of love to deny self and to give to others...We can only have such love when Christ is free to work His own love through us. We cannot fulfill any of Christ’s commands without Christ Himself, least of all His command to love. We can only love as Christ loves when He has free reign in our hearts...When the Spirit empowers our lives and Christ is obeyed as the Lord of our hearts, our sins and weaknesses are dealt with and we find ourselves wanting to serve others, wanting to sacrifice for them and serve them—because Christ’s loving nature has truly become our own. Loving is the supernatural attitude of the Christian, because love is the nature of Christ. When a Christian does not love he has to do so intentionally and with effort—just as he must do to hold his breath. To become habitually unloving he must habitually resist Christ as the Lord of his heart. To continue the analogy to breathing, when Christ has his proper place in our hearts, we do not have to be told to love—just as we do not have to be told to breathe. Eventually it must happen, because loving is as natural to the spiritual person as breathing is to the natural person. Though it is unnatural for the Christian to be unloving, it is still possible to be disobedient in regard to love. Just as loving is determined by the will and not by circumstances or other people, so is not loving. If a husband fails in his love for his wife, or she for him, it is never because of the other person, regardless of what the other person may have done. You do not fall either into or out of agape love, because it is controlled by the will. Romantic love can be beautiful and meaningful, and we find many favorable accounts of it in Scripture. But it is agape love that God commands husbands and wives to have for each other (see notes Ephesians 5:25; Ephesians 5:28; Ephesians 5:33 cf. notes Titus 2:4; etc.)—the love that each person controls by his own act of will. Strained relations between husbands and wives, between fellow workers, between brothers and sisters, or between any others is never a matter of incompatibility or personality conflict but is always a matter of sin...Loving others is an act of obedience, and not loving them is an act of disobedience. (Ibid)

"The absence of (agape) love is the presence of sin. The absence of love has nothing at all to do with what is happening to us, but everything to do with what is happening in us. Sin and love are enemies, because sin and God are enemies. They cannot coexist. Where one is, the other is not. The loveless life is the ungodly life; and the godly life is the serving, caring, tenderhearted, affectionate, self–giving, self–sacrificing life of Christ’s love working through the believer. (Ibid)

Agape love centers on the needs and welfare of the one loved and will pay whatever personal price is necessary to meet those needs and foster that welfare." (MacArthur, J: Romans 1-8. Chicago: Moody Press; MacArthur, J: Romans 9-16. Chicago: Moody Press)

Agape is the love that gives. There’s no taking involved. It is completely unselfish. It seeks the highest good for another no matter what the cost, demonstrated supremely by Christ’s sacrifice on our behalf." (MacArthur, J. Saved Without A Doubt. Wheaton, Ill.: May, 2006. Victor Books)

Forbearing love could only be agape love, because only agape love gives continuously and unconditionally. Eros love is essentially self–love, because it cares for others only because of what it can get from them. It is the love that takes and never gives. Philia love is primarily reciprocal love, love that gives as long as it receives. But agape love is unqualified and unselfish love, love that willingly gives whether it receives in return or not. It is unconquerable benevolence, invincible goodness—love that goes out even to enemies and prays for its persecutors (see notes Matthew 5:43; Matthew 5:44). That is why the forbearance of which Paul speaks here could only be expressed in agape love." (MacArthur, J: Ephesians. 1986. Chicago: Moody Press)

Giving of oneself to others is the epitome of agape love. Biblical love is not a pleasant emotion or good feeling about someone, but the giving of oneself for his welfare (cf. 1 John 3:16). Divine love is unconditional love, love that depends entirely on the one who loves and not on the merit, attractiveness, or response of the one loved. Christ did not simply have a deep feeling and emotional concern for mankind. Nor did He sacrifice Himself for us because we were deserving. God’s love, and all love that is like His, loves for the sake of giving, not getting With conditional love, if the conditions are not met there is no obligation to love. If we do not get, we do not give. But God’s makes no conditions for His love to us and commands that we love others without conditions. There is no way to earn God’s love or to deserve it by reason of human goodness. Romantic, emotional love between husband and wife ebbs and flows, and sometimes disappears altogether. But loss of romantic love is never an appropriate excuse for dissolving a marriage, because the love that God specifically commands husbands to have for their wives is agape love (see notes Ephesians 5:25; Ephesians 3:19; cf. notes Titus 2:4; etc.)—love like His own undeserved love for us, love that is based on willful choice in behalf of the one loved, regardless of emotions, attraction, or deserving. Romantic love enhances and beautifies the relationship between husband and wife, but the binding force of a Christian marriage is God’s own kind of love, the love that loves because it is the divine nature to love. It is the love of giving, not of getting; and even when it ceases to get, it continues to give. Where there is the sacrificial love of willful choice, there is also likely to be the love of intimacy, feeling, and friendship (philia)...Those who are given God’s nature through Jesus Christ are commanded to love as God loves. In Christ, it is now our nature to love just as it is God’s nature to love—because His nature is now our nature. For a Christian not to love is for him to live against his own nature as well as against God’s. Lovelessness is therefore more than a failure or shortcoming. It is sin, willful disobedience of God’s command and disregard of His example." (MacArthur, J: Ephesians. 1986. Chicago: Moody Press)

Agape is impossible for unconverted to manifest this divine love & in fact it is impossible even for a believer to demonstrate it in his own strength. It can only be exhibited by the power of the indwelling Holy Spirit. A believer has this love (divine nature) within (see note Colossians 1:27) and it is progressively manifest more and more as fruit by the Holy Spirit (Gal 5:22) as we obey God's truth.  Agape love willingly engages in self-sacrificing action to procure the loved one's highest good.

Love's perfect expression on earth is the Lord Jesus Christ and He defines this sacrificial love for He left heaven, came to earth, took on a human form, was spit on and mocked, was crowned with a crown of thorns, nailed to a cross, abused, and had a spear thrust into His side. He loved the church enough to die for her. That's sacrificial love.

Donald W. Burdick gives the following excellent summary of agape love:

It is spontaneous. There was nothing of value in the persons loved that called forth such sacrificial love. God of His own free will set His love on us in spite of our enmity and sin. [Agape] is love that is initiated by the lover because he wills to love, not because of the value or lovableness of the person loved. [Agape] is self-giving. and is not interested in what it can gain, but in what it can give. It is not bent on satisfying the lover, but on helping the one loved whatever the cost. [Agape] is active and is not mere sentiment cherished in the heart. Nor is it mere words however eloquent. It does involve feeling and may express itself in words, but it is primarily an attitude toward another that moves the will to act in helping to meet the need of the one loved. (Burdick, D W: The Letters of John the Apostle (Chicago: Moody, 1985, page 351)

As noted below Barclay has labeled agape as unconquerable benevolence for nothing the other person can do will make us seek anything but their highest good and to never feel bitterness or desire for revenge. Though the one loved even injure us and insult us, agape will never feel anything but kindness towards him. Agape gives & gives & gives. Agape takes slaps in the face and still gives even as Jesus did saying Father forgive them. Agape is not withheld. That clearly means that this Christian love is not an emotional or sentimental thing. It is the ability to retain unconquerable goodwill to the unlovely and the unlovable, towards those who do not love us, and even towards those whom we do not like.

William Barclay notes that agape indicates an...

unconquerable benevolence, invincible goodwill...If we regard a person with agape, it means that no matter what that person does to us, no matter how he treats us, no matter if he insults us or injures us or grieves us, we will never allow any bitterness against him to invade our hearts, but will regard him with that unconquerable benevolence and goodwill which will seek nothing but his highest good."...In the case of our nearest and our dearest we cannot help loving them; we speak of falling in love; it is something which comes to us quite unsought; it is something which is born of the emotions of the heart. But in the case of our enemies, (agape) love is not only something of the heart; it is also something of the will. It is not something which we cannot help; it is something which we have to will ourselves into doing (Ed note: enabled by the Spirit Whose "fruit" in yielded believers is "agape love"). It is in fact a victory over that which comes instinctively to the natural man. Agape does not mean a feeling of the heart, which we cannot help, and which comes unbidden and unsought; it means a determination of the mind, whereby we achieve this unconquerable goodwill even to those who hurt and injure us. Agape, someone has said, is the power to love those whom we do not like and who may not like us. In point of fact we can only have agape when Jesus Christ enables us to conquer our natural tendency to anger and to bitterness, and to achieve this invincible goodwill to all men.

Agape, is that unconquerable benevolence, that undefeatable good-will, which will never seek anything but the highest good of others, no matter what they do to us, and no matter how they treat us. That love can come to us only when Christ, Who is that love, comes to dwell within our hearts..."

(Agape) ...will never dream of revenge, but will meet all injuries and rebuffs with undefeatable good will. Agape is that quality of mind and heart which compels a Christian never to feel any bitterness, never to feel any desire for revenge, but always to seek the highest good of every man no matter what he may be. If a man has agape, no matter what other people do to him or say of him, he will seek nothing but their good. He will never be bitter, never resentful, never vengeful; he will never allow himself to hate; he will never refuse to forgive.

Love, agape, is the virtue of the man who, even if he tried, could not forget what God has done for him nor the love of God to men.

Agape is the word for Christian love. Agape is not passion with its ebb and flow, its flicker and its flame; nor is it an easy-going and indulgent sentimentalism. And it is not an easy thing to acquire or a light thing to exercise. Agape is undefeatable goodwill; it is the attitude towards others which, no matter what they do, will never feel bitterness and will always seek their highest good. There is a love which seeks to possess; there is a love which softens and enervates; there is a love which withdraws a man from the battle; there is a love which shuts its eyes to faults and to ways which end in ruin. But Christian love will always seek the highest good of others and will accept all the difficulties, all the problems and all the toil which search involves. (Barclay, W: The Daily Study Bible Series, Rev. ed. Philadelphia: The Westminster Press) (Bolding added)

F. E. Marsh writes that...

Love has not an irritating thorn in its hand, nor a jealous look in its eye, nor depreciating words on its lips, nor sore feelings in its heart. Love sees the best in others, and the worst in itself. Love will wash another’s feet, and think it is honored by so doing

A Peanuts cartoon shows Lucy standing with her arms folded and a stern expression on her face. Charlie Brown pleads, "Lucy, you must be more loving. This world really needs love. You have to let yourself love to make this world a better place." Lucy angrily whirls around and knocks Charlie Brown to the ground. She screams at him, "Look, Blockhead, the world I love. It's people I can't stand."

Tertullian the early disciple wrote,

It is our care for the helpless, our practice of lovingkindness, that brands us in the eyes of many of our opponents. 'Look!' they say, 'How they love one another!' Look how they are prepared to die for one another."

People do not care how much we know
until they know how much we care.