A.T. Robertson Commentary Galatians 2:17

"But if, while we sought to be justified in Christ, we ourselves also were found sinners, is Christ a minister of sin? God forbid." — Galatians 2:17 (ASV)

We ourselves were found sinners (ευρεθημεν κα αυτο αμαρτωλο). Like the Gentiles, Jews who thought they were not sinners, when brought close to Christ, found that they were. Paul felt like the chief of sinners.

A minister of sin (αμαρτιας διακονος). Objective genitive, a minister to sin. An illogical inference. We were sinners already in spite of being Jews. Christ simply revealed to us our sin.

God forbid (μη γενοιτο). Literally, "May it not happen." Wish about the future (μη and the optative).