1John 4:1-3 (NIV)
Dear friends, do not believe every spirit, but
test the spirits to see whether they are from
God, because many false prophets have
gone out into the world.
2 This is how you can
recognize the Spirit of God: Every spirit
that acknowledges that Jesus Christ has come
in the flesh is from God,
3 but every spirit
that does not acknowledge Jesus is not from
God. This is the spirit of the antichrist, which
you have heard is coming and even now is
already in the world.