The one preach Christ of contention, not sincerely, supposing to add affliction to my bonds: Preach Christ of contention - The Judaizing teachers, they also preach Christ; they acknowledge that Jesus is the Christ or promised Messiah, and preach him as such.
Not sincerely - Ουχ ἁγνως· Not chastely, garbling the Gospel; not speaking the whole truth, but just what served their purpose; and at the same time they denounced the apostle as an enemy to the Divine institutions, because he spoke against circumcision.