Sometimes He said: "I came forth from the Father, and am come into the world" (John 16:28), that is, the Father out of love for us sent from heaven into the world His Only-begotten Son. Sometimes even more clearly: "God so loved the world, that He gave His Only-begotten Son, that whosoever believeth in Him should not perish" (John 3:16); and: "I came not to judge the world, but to save the world" (John 12:47). So then, we ourselves have both seen, and from the Only-begotten, who is in the bosom of the Father (John 1:18), have heard, and from the action—mutual love—we know that God is in us, and has given us of His Spirit, and we are in communion with Him.
1 John 4:15. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.
1 John 4:16. And we have known the love that God has for us, and have believed in it. God is love, and he who abides in love abides in God, and God in him.
This refers to what was said a little above (v. 2): every spirit that confesses the Lord Jesus, who has come in the flesh. The apostle has sufficiently proved that believers are children of God and that God abides in them; and he proved this by love for one another, because the Holy Spirit was given to them. After this he returns to the aforementioned discourse and says: whoever confesses that Jesus is the Son of God, God abides in him, because, as was said above, every spirit that confesses Jesus Christ, who has come in the flesh, is from God. With these words the apostle also expresses another truth, that those who so confess and have the Spirit abiding in them, that is, God, themselves also abide in God. In what way? Through love for one another. And having recalled love, he repeats everything he has said about love, in order to more firmly establish the teaching about love.
1 John 4:17. Love reaches such perfection in us that we have boldness in the day of judgment, because we conduct ourselves in this world as He does.
1 John 4:18. There is no fear in love, but perfect love casts out fear, because fear involves torment.
God is light, and His saints, according to the saying of the Gospel (Matt. 5:14), are the light of the world and are free from the fear of torment, because they are filled with love for God. I desire, says the apostle, that you be perfected in love so that on the day of judgment we may have boldness before God, because He Himself is the Judge, according to His own saying: "The Father judges no one, but has given all judgment to the Son" (John 5:22). And that our boldness will be before God incarnate, the apostle expressed in the following words: "we conduct ourselves in this world as He did," that is, when we have already demonstrated that God is in us and we in Him, then we ourselves are witnesses to the perfection of love. As He was blameless and pure in the world, which is why He also said: "the ruler of this world is coming, and he has nothing in Me" (John 14:30), so we too shall be in God and God in us. If He is the teacher and giver of our purity, then we must bear Him in the world purely and blamelessly, "always carrying about in the body His dying" (2 Cor. 4:10). If we live in this way, then we shall have boldness before Him and shall be free from all fear. For, having attained perfection in love through good deeds, we shall be far from fear. In confirmation of this he also adds: perfect love casts out fear. What fear? He himself says that it is the fear of torment.
For it is possible to love someone even out of fear of punishment. But such fear is not perfect, that is, it is not characteristic of perfect love. Having said this about perfect love, he necessarily says that we must love God because He first loved us, and since He first did us good, we must all the more compel ourselves to repay Him for it. Based on the words of David: "Fear the Lord, you His saints, for there is no want to those who fear Him" (Ps. 33:10), some will ask: how does John now say that perfect love casts out fear? Are God's saints really so imperfect in love that they are commanded to fear? We answer. Fear is of two kinds. One is introductory, to which torment is attached.
A person who has committed evil deeds approaches God with fear, and approaches in order not to be punished. This is the preliminary fear. The other fear is perfect. This fear is free from such dread; which is why it is called pure and enduring forever (Ps. 18:10). What then is this fear, and why is it perfect? Because the one who possesses it is completely captivated by love and strives in every way to lack nothing of what one who loves deeply must do for the beloved.
1 John 4:18. He who fears is not made perfect in love.
1 John 4:19. Let us love Him, because He first loved us.
By fear here is meant the preliminary fear. Whoever sincerely loves God does what is pleasing to Him not out of fear of punishment, but out of an inclination toward virtue and out of love for God, not safeguarding himself even with the lawful fear that consists in love for what is good. And that fear which does something in order not to fall under punishment is identical with the first. Therefore it is also added: "fear has torment."
1 John 4:20. Whoever says, "I love God," but hates his brother, is a liar; for he who does not love his brother whom he sees, how can he love God, Whom he does not see?
Above, the apostle insistently proved that love must be mutual, passing from God to us and from us to God; he added to this that if God so loved us, then we also ought to love one another. Now he again raises the discourse to the same point and says: since the duty lies upon us to love our brother, following the example of God's love for us, and by rendering love to God we fulfill this duty, we must certainly love our brother as the most perfect proof of love for God. For if this does not exist, then our love for God will not be preserved either, since the duty toward our neighbors — a duty flowing from the love of God — will have been violated. He adds an even stronger word for the reproach of those who wish to pervert divine love.
The Apostle speaks as if to say: love is evidently formed through association with one another; and association presupposes that a person sees his brother and through interaction with him becomes even more attached to him by love, for seeing greatly draws one to love. If this is so, then he who makes nothing of that which draws far more to love, and does not love the brother whom he has seen, how can he be regarded as truthful when he says that he loves God, Whom he has not seen, Who is neither in association with him nor grasped by any sense? If anyone shamelessly says that he loves God but hates his brother, that person, perverting divine love, proves himself beyond this to be also a transgressor of His following commandment: "By this shall all men know that ye are My disciples, if ye have love one to another" (John 13:35). Therefore, whoever loves God and strives to be His disciple, by His commandment, loves his brother also.
1 John 4:21. And we have this commandment from Him, that he who loves God should love his brother also.