1 John 4:1-6
Intro
(1 John 4 [KJV])
[1] Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.
[2] Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God:
[3] And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world.
[4] Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.
[5] They are of the world: therefore speak they of the world, and the world heareth them.
[6] We are of God: he that knoweth God heareth us; he that is not of God heareth not us. Hereby know we the spirit of truth, and the spirit of error.
We can test if someone is a believer by testing him according to 1 John 4:1-6.