1 John 4:1-6

Beloved, believe not every spirit, but prove the spirits, whether they are of God: because many false prophets are gone out into the world. Hereby know ye the Spirit of God: every spirit which confesseth that Jesus Christ is come in the flesh is of God: and every spirit which confesseth not Jesus is not of God: and this is the spirit of the antichrist, whereof ye have heard that it cometh; and now it is in the world already. Ye are of God, my little children, and have overcome them: because greater is he that is in you than he that is in the world. They are of the world: therefore speak they as of the world, and the world heareth them. We are of God: he that knoweth God heareth us; he who is not of God heareth us not. By this we know the spirit of truth, and the spirit of error.