Augustine of Hippo : Quarrels should be unknown among you, or at least, if they arise, they should as quickly as possible be ended, lest anger grow into hatred, and convert "a mote into a beam," and make the soul chargeable with murder. For the saying of Scripture: "He that hateth his brother is a murderer," does not concern men only, but women also are bound by this law through its being enjoined on the other sex, which was prior in the order of creation. Let her, whoever she be, that shall have injured another by taunt or abusive language, or false accusation, remember to remedy the wrong by apology as promptly as possible, and let her who was injured grant forgiveness without further disputation. If the injury has been mutual, the duty of both parties will be mutual forgiveness, because of your prayers, which, as they are more frequent, ought to be all the more sacred in your esteem. — Letters 211 Augustine of Hippo : Do you hate your brother or not? But if you despise hatred, listen to what you do not heed: Whoever hates his brother is a murderer. Whoever hates is a murderer. You have not prepared poison. Can you now say: "What does it matter to me if I am a murderer?" Whoever hates is a murderer. You did not prepare poison. You did not proceed to strike the enemy with the sword. You did not prepare an instrument of crime, nor a place, nor a time. Lastly, you did not commit the very crime. You only hated, and you killed yourself before him. Therefore, learn justice so that you do not hate except the vices, love men. If you hold this, and do this justice, so that you also prefer the men even the vicious to be healed rather than condemned, you have done a good work in the vineyard. — Sermon 49 Augustine of Hippo : Lest ye should think it a light matter, brethren, to hate, or, not to love, hear what follows: "Every one that hateth his brother, is a murderer." How now, if any made light of hating his brother, will he also in his heart make light of murder? He does not stir his hands to kill a man; yet he is already held by God a murderer; the other lives, and yet this man is already judged as his slayer! "Every one that hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him." — Ten Homilies on 1 John 5 Bede : Everyone who hates his brother is a murderer. If anyone despised brotherly hatred, would he also despise murder in his heart? He does not move his hands to kill a man, yet he is already considered a murderer by God. That man lives, but this one is already judged a killer. — Commentary on the Catholic Epistles Bede : And you know that no murderer has eternal life abiding in him. Even if he seems to live among the saints through faith here, he does not have eternal life abiding in him. For when the time of retribution comes, he will be damned with Cain who was of the evil one, even he who is guilty of this kind of murder, so as to disagree and dissent and have no peace with his brothers. Note that he does not say absolutely, "A murderer does not have life in him," but, "Everyone," he says, "who is a murderer." Certainly not only he who uses a weapon, but also he who follows his brother with hatred. — Commentary on the Catholic Epistles Caesarius of Arles : In this passage, every person should be regarded as a brother, for we are all brothers in Christ. — SERMONS 219.2 Clement of Alexandria ((as quoted by Cassiodorus)) : "Every one who hates his brother is a murderer." For in him through unbelief Christ dies. Rightly, therefore, he continues, "And you know that no murderer and unbeliever has eternal life abiding in him." For the living Christ abides in the believing soul. — From the Latin Translation of Cassiodorus Clement of Alexandria : And if we owe our lives to the brethren, and have made such a mutual compact with the Saviour, why should we any more hoard and shut up worldly goods, which are beggarly, foreign to us and transitory? Shall we shut up from each other what after a little shall be the property of the fire? Divinely and weightily John says, "He that loveth not his brother is a murderer," the seed of Cain, a nursling of the devil. He has not God's compassion. He has no hope of better things. He is sterile; he is barren; he is not a branch of the ever-living supercelestial vine. He is cut off; he waits the perpetual fire. — Who is the Rich Man that Shall Be Saved? Cyprian : Finally, such are crowned by the Lord, such will be avenged with the Lord in the day of judgment; but the quarrelsome and disunited, and he who has not peace with his brethren, in accordance with what the blessed apostle and the Holy Scripture testifies, even if he have been slain for the name of Christ, shall not be able to escape the crime of fraternal dissension, because, as it is written, "He who hateth his brother is a murderer" and no murderer attains to the kingdom of heaven, nor does he live with God. He cannot be with Christ, who had rather be an imitator of Judas than of Christ. How great is the sin which cannot even be washed away by a baptism of blood-how heinous the crime which cannot be expiated by martyrdom! — Treatise IV. On the Lord's Prayer. Cyprian : Why do you rush into the darkness of jealousy? why do you enfold yourself in the cloud of malice? why do you quench all the light of peace and charity in the blindness of envy? why do you return to the devil, whom you had renounced? why do you stand like Cain? For that he who is jealous of his brother, and has him in hatred, is bound by the guilt of homicide, the Apostle John declares in his epistle, saying, "Whosoever hateth his brother is a murderer; and ye know that no murderer hath life abiding in him." And again: "He that saith he is in the light, and hateth his brother, is in darkness even until now, and walketh in darkness, and knoweth not whither he goeth, because that darkness hath blinded his eyes." Whosoever hates, says he, his brother, walketh in darkness, and knoweth not whither he goeth. For he goeth unconsciously to Gehenna, in ignorance and blindness; he is hurrying into punishment, departing, that is, from the light of Christ, who warns and says, "I am the light of the world. He that followeth me shall not walk in darkness, but shall have the light of life." But he follows Christ who stands in His precepts, who walks in the way of His teaching, who follows His footsteps and His ways, who imitates that which Christ both did and taught; in accordance with what Peter also exhorts and warns, saying, "Christ suffered for us, leaving you an example that ye should follow His steps." — Treatise X. On Jealousy and Envy. Tertullian : But how far wider an extent the Lord assigns to those crimes we are sure: when He defines adultery to consist even in concupiscence, "if one shall have cast an eye lustfully on," and stirred his soul with immodest commotion; when He judges murder to consist even in a word of curse or of reproach, and in every impulse of anger, and in the neglect of charity toward a brother just as John teaches, that he who hates his brother is a murderer. — On Idolatry