A.T. Robertson Commentary Galatians 2:15

"We being Jews by nature, and not sinners of the Gentiles," — Galatians 2:15 (ASV)

Not sinners of the Gentiles (ουκ εξ εθνων αμαρτωλο). The Jews regarded all Gentiles as "sinners" in contrast with themselves (cf. Matthew 26:45 "sinners" and Lu 18:32 "Gentiles"). It is not clear whether verses 15-21 were spoken by Paul to Peter or whether Paul is now simply addressing the Galatians in the light of the controversy with Peter. Burton thinks that he is "mentally addressing Peter, if not quoting from what he said to him."