John Calvin Commentary Romans 3:1

"What advantage then hath the Jew? or what is the profit of circumcision?" — Romans 3:1 (ASV)

Although Paul has clearly proved that bare circumcision brought nothing to the Jews, yet since he could not deny that there was some difference between the Gentiles and the Jews, which was sealed to them by the Lord through that symbol, and since it was inconsistent to make a distinction authored by God void and meaningless, it remained for him also to remove this objection.

It was indeed evident that the glorying in which the Jews indulged on this account was foolish; yet a doubt still remained as to the design of circumcision, for the Lord would not have appointed it unless some benefit had been intended. He therefore, by way of an objection, asks what made the Jew superior to the Gentile; and he adds a reason for this with another question, What is the benefit of circumcision? For this separated the Jews from the common class of people; it was a partition wall, as Paul calls ceremonies, which kept groups apart.