Response: Carefully read the referenced verses:
“By this you know the Spirit of God: every spirit which confesses that Jesus Christ has come in the flesh is from God. And every spirit which does not confess that Jesus Christ has come in the flesh is not from God; and this is the antichrist which you heard is coming, and now is already in the world.” (1 John 4:2-3)
(Picture on right The Deeds of Antichrist by Luca Signorelli, c. 1505)
“Because many deceivers entered into the world, those not confessing Jesus Christ to have come in the flesh, this is the deceiver and the antichrist.” (2 John 1:7)
Nowhere in these verses is anything said about God coming in the flesh.
Trinitarians read something into these passages which is not there.
One of the earliest heresies was Gnosticism which taught that the spirit was good, but the flesh was inherently evil. Therefore, Gnostics did not believe that Jesus was really a flesh and blood human, but only appeared to be so. This is the error against which John was warning.
Biblical monotheists believe that Jesus Christ truly was the miraculously-conceived, spirit-anointed flesh and blood Son of God.
(For details see Response in Proposition # 2)