John asks us not to believe every spirit but to test the spirits to see whether they are from God, because many false prophets have gone out into the world. Every spirit that confesses that Jesus Christ has come in the flesh is from God, and every spirit that does not confess Jesus is not from God but is the spirit of the antichrist. Believers are from God and have overcome those false teachers, for he who is in them is greater than he who is in the world. They are from the world and the world listens to them, but whoever knows God listens to the apostles (vv. 1-6).
Let us love one another, for love is from God, and everyone who loves has been born of God and knows him. Anyone who does not love does not know God, because God is love. God's love was made manifest by sending his only Son into the world so that we might live through him. Love consists not in our loving God but in his loving us and sending his Son as the propitiation for our sins. If God so loved us, we ought to love one another. No one has ever seen God, but if we love one another, God abides in us and his love is perfected in us (vv. 7-12).
We know that we abide in him because he has given us of his Spirit. The apostles have seen and testify that the Father sent the Son as Savior of the world. Whoever confesses that Jesus is the Son of God abides in God. God is love, and whoever abides in love abides in God. Love is perfected in us so that we may have confidence on the day of judgment. There is no fear in love, but perfect love casts out fear, for fear has to do with punishment. We love because he first loved us. If anyone says he loves God and hates his brother, he is a liar, for whoever does not love his brother whom he has seen cannot love God whom he has not seen. This commandment we have from him: whoever loves God must also love his brother (vv. 13-21).