1 John 4:1-4

1 Beloved, don't believe every spirit, but test the spirits, whether they are of God, because many false prophets have gone out into the world.  2 By this you know the Spirit of God: every spirit who confesses that Jesus Christ has come in the flesh is of God,  3 and every spirit who doesn't confess that Jesus Christ has come in the flesh is not of God, and this is the spirit of the antichrist, of whom you have heard that it comes. Now it is in the world already.  4 You are of God, little children, and have overcome them; because greater is he who is in you than he who is in the world.