1 John 4:2-4

Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: 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. 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.