Albert Barnes Commentary Romans 3:29

"Or is God [the God] of Jews only? is he not [the God] of Gentiles also? Yea, of Gentiles also:" — Romans 3:29 (ASV)

Is he the God, etc. The Jews supposed that he was the God of their nation only, that they only were to be admitted to his favour. In these verses Paul showed that as all had alike sinned, Jews and Gentiles, and as the plan of salvation by faith was adapted to sinners, without any special reference to Jews, so God could show favours to all, and all might be admitted on the same terms to the benefits of the plan of salvation.