Galatians 2:7

As to Peter was that of the circumcision. Calvin pretends to prove by this, that St. Peter and his successors are not head of the whole Church, because St. Peter was only the apostle of the Jews. But St. Paul speaks not here of the power and jurisdiction, but of the manner that St. Peter and he were to be employed. It was judged proper that St. Peter would preach chiefly to the Jews, who had been the elect people of God, and that St. Paul should be sent to the Gentiles; yet both of them preached both to Jews and Gentiles: and St. Peter, by receiving Cornelius, first opened the gate of salvation to the Gentiles, as he says of himself, (Acts xv. 7.) that God made choice of him, that the Gentiles by his mouth should hear the gospel, and believe. That St. Peter was head of the Church, see the notes on Matthew xvi. and John xxi. (Witham)