1 John 4:1-3 Revised Standard Version Catholic Edition (RSVCE)
Testing the Spirits
4 Beloved, do not believe every spirit, but test the spirits[a] to see whether they are of God; for many false prophets have gone out into the world. 2 By this you know the Spirit of God: every spirit which confesses that Jesus Christ has come in the flesh is of God, 3 and every spirit which does not confess Jesus is not of God. This is the spirit of antichrist, of which you heard that it was coming, and now it is in the world already.