What spirits are of God, and what are not. We must love one another, because God has loved us.
4:1. Dearly beloved, believe not every spirit, but try the spirits if they be of God: because many false prophets are gone out into the world.
Try the spirits.... Viz., by examining whether their teaching be agreeable to the rule of the Catholic faith, and the doctrine of the church. For as he says, (ver. 6,) He that knoweth God, heareth us [the pastors of the church]. By this we know the spirit of truth, and the spirit of error.
4:2. By this is the spirit of God known. Every spirit which confesseth that Jesus Christ is come in the flesh is of God:
Every spirit which confesseth, etc.... Not that the confession of this point of faith alone, is, at all times, and in all cases, sufficient; but that with relation to that time, and for that part of the Christian doctrine, which was then particularly to be confessed, taught, and maintained against the heretics of those days, this was the most proper token, by which the true teachers might be distinguished form the false.
4:3. And every spirit that dissolveth Jesus is not of God. And this is Antichrist, of whom you have heard that he cometh: and he is now already in the world.
That dissolveth Jesus.... Viz., either by denying his humanity, or his divinity. He is now already in the world.... Not in his person, but in his spirit, and in his precursors.
4:4. You are of God, little children, and have overcome him. Because greater is he that is in you, than he that is in the world.
4:5. They are of the world. Therefore of the world they speak: and the world heareth them.
4:6. We are of God. He that knoweth God heareth us. He that is not of God heareth us not. By this we know the spirit of truth and the spirit of error.