1 John 4:2-4

Amplified Bible

² By this you know and recognize the Spirit of God: every spirit that acknowledges and confesses [the fact] that Jesus Christ has [actually] come in the flesh [as a man] is from God [God is its source]; ³ and every spirit that does not confess Jesus [acknowledging that He has come in the flesh, but would deny any of the Son’s true nature] is not of God; this is the spirit of the antichrist, which you have heard is coming, and is now already in the world. ⁴ Little children (believers, dear ones), you are of God and you belong to Him and have [already] overcome them [the agents of the antichrist]; because He who is in you is greater than he (Satan) who is in the world [of sinful mankind].