In this the children of God are manifest, and the children of the devil. Whosoever is not just, is not of God, nor he that loveth not his brother.

“Wherein? except it be (thus): the former by not sinning, from the time that they were born from God; the latter by sinning, because they are from the devil, just as if they never were born from God? But if he says, "He who is not righteous is not of God," how shall he who is not modest again become (a son) of God, who has already ceased to be so?”

“And the apostles, who speak of God, in establishing the truth of the advent of the Lord Jesus Christ, have each of them indicated the appearing of these abominable and ruin-working men, and have openly announced their lawless deeds. First of all Peter, the rock of the faith, whom Christ our God called blessed, the teacher of the Church, the first disciple, he who has the keys of the kingdom, has instructed us to this effect: "Know this first, children, that there shall come in the last days scoffers, walking after their own lusts. And there shall be false teachers among you, who privily shall bring in damnable heresies." After him, John the theologian, and the beloved of Christ, in harmony with him, cries, "The children of the devil are manifest; and even now are there many antichrists; but go not after them. Believe not every spirit, because many false prophets are gone out into the world." And then Jude, the brother of James, speaks in like manner: "In the last times there shall be mockers, walking after their own ungodly lusts. There be they who, without fear, feed themselves." You have observed the concord of the theologians and apostles, and the harmony of their doctrine.”

“That charity and brotherly affection are to be religiously and stedfastly practised. ...Of this same thing in the Epistle of John: "In this appear the children of God and the children of the devil. Whosoever is not righteous is not of God, and he who loveth not his brother. For he who hateth his brother is a murderer; and ye know that no murderer hath eternal life abiding in him."”

“The chief author of sin is the devil, the begetter of all sin. Before him, no one sinned. Nor did he sin because he was by nature prone to sin (since in that case the responsibility for his sin would lie with his Creator). Rather, being created good he became a devil by his own free choice, receiving that name from his willed action. Though he was originally an archangel, he became a slanderer (diabolos), because of his slandering.”

“"In this are manifested the children of God and the children of the devil. Whosoever is not righteous is not of God, neither he that loveth not his brother." Aye, now indeed it is manifest of what he speaks: "Neither he that loveth not his brother." Therefore, love alone puts the difference between the children of God and the children of the devil. Let them all sign themselves with the sign of the cross of Christ; let them all respond, Amen; let all sing Alleluia; let all be baptized, let all come to church, let all build the walls of churches: there is no discerning of the children of God from the children of the devil, but only by charity. They that have charity are born of God: they that have it not, are not born of God. A mighty token, a mighty distinction! Have what thou wilt; if this alone thou have not, it profiteth thee nothing: other things if thou have not, have this, and thou hast fulfilled the law. "For he that loveth another hath fulfilled the law," saith the apostle: and, "Charity is the fulfilling of the law." I take this to be the pearl which the merchant man in the Gospel is described to have been seeking, who "found one pearl, and sold all that he had, and bought it." This is the pearl of price, Charity, without which whatever thou mayest have, profiteth thee nothing: which if alone thou have, it sufficeth thee.”

“In this the children of God are manifest,.... By regenerating grace, and not sinning, in the sense before explained, in consequence of it: adoption is an act of God's grace and sovereign will; it is secret in his own heart, and is secured in divine predestination, and in the covenant of grace, and is antecedent to regeneration: regeneration and faith do not make men the children of God, but manifest them to be so; adoption makes them the children of God, and entitles them to the inheritance; regeneration gives them the nature of the children of God, and makes them meet for it, and manifests their right unto it; not to the men of the world, but to themselves and other saints: and the children of the devil; such as imitate him, do his will and his lusts, and are openly under his power and influence; these are distinguishable from regenerate persons, and the children of God, by their lives and conversations; so the people of the nations of the world are called, "the children of Samael", and the serpent, by the Jews (m), which are with them the names of the devil. Whosoever doth not righteousness is not of God: that is, he does; not appear to be born of God, who does not by faith lay hold on the righteousness of Christ for his justification before God, and acceptance with him; and who does not do works of righteousness in faith from a principle of love, and with a view to the glory of God; for where regenerating grace is, there will be such graces and such practices: neither he that loveth not his brother; for as he that loveth God, and Christ, and the brethren, appears manifestly to be born again, and to have passed from death to life, so he that does not is in darkness, in a state of unregeneracy, and walks and continues therein; for was he born again, he would be taught of God to love the saints; see Jo1 4:7. (m) Raya Mehimna in Zohar in Lev. fol. 34. 2.”

“In this the children of God are manifest - Here is a fearful text. Who is a child of the devil? He that commits sin. Who is a child of God? He that works righteousness. By this text we shall stand or fall before God, whatever our particular creed may say to the contrary. Neither he that loveth not his brother - No man is of God who is not ready on all emergencies to do any act of kindness for the comfort, relief, and support of any human being. For, as God made of one blood an the nations of men to dwell upon the face of the whole earth, so all are of one family; and consequently all are brethren, and should love as brethren.”

“children of the devil--(See on Jo1 3:8; Act 13:10). There is no middle class between the children of God and the children of the devil. doeth not righteousness--Contrast Jo1 2:29. he that loveth not his brother-- (Jo1 4:8); a particular instance of that love which is the sum and fulfilment of all righteousness, and the token (not loud professions, or even seemingly good works) that distinguishes God's children from the devil's.”