1 John 4:1-3

BELOVED, DO not put faith in every spirit, but prove (test) the spirits to discover whether they proceed from God; for many false prophets have gone forth into the world. By this you may know (perceive and recognize) the Spirit of God: every spirit which acknowledges and confesses [the fact] that Jesus Christ (the Messiah) [actually] has become man and has come in the flesh is of God [has God for its source]; And every spirit which does not acknowledge and confess that Jesus Christ has come in the flesh [but would annul, destroy, sever, disunite Him] is not of God [does not proceed from Him]. This [nonconfession] is the [spirit] of the antichrist, [of] which you heard that it was coming, and now it is already in the world.