As he says also in Hosea,
I will call them my people, who were not my people; and her beloved, who was not beloved.
All Commentaries on Romans 9:25 Go To Romans 9
Augustine of Hippo
AD 430
The gist of the entire argument leads to this conclusion. Paul taught that we do good by the mercy of God and that the Jews who had received the gospel should not glory in their works, thinking that they had deserved this and not wanting it to be given to the Gentiles. In Paul’s mind, the Jews should cease from such pride and understand that if we are called to faith not through our own works but by the mercy of God and if it is given to those who believe to do good, then they should not begrudge the Gentiles this mercy as if it had been given to the Jews on the ground of prior merit, which is nothing.