Or is God the God of Jews only? Is he not the God of Gentiles also? Yes, of Gentiles also,
29. Is he the God of the Jews only? The second proposition is, that this righteousness belongs no more to the Jews than to the Gentiles: and it was a great matter that this point should be urged, in order that a free passage might be made for the kingdom of Christ through the whole world.
From all this Paul infers that it is in vain to look for justification by the works of the law, and that it is to be had only by faith, which is the point he has been all along proving, from Rom 1:17, and which he lays down (Rom 3:28) as the summary of his discourse, with a quod erat demonstrandum - which was to be demonstrated.
Commenting on Romans 3:19-31
Verses 29, 30. 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...