Last time I said that God’s unmerited mercy was being poured out on vessels of wrath: stupid, pagan Gentiles who weren’t even looking for God in the first place—but what about Israel, these vessels that were prepared beforehand for glory? What about their fate?
Paul’s overarching point, if you recall, is especially concerned with the salvation of unsaved Israel—a point that seems to be quickly ignored in many debates. If the argument here is that God has decided not to save Israel there is truly a problem with God’s word which will always stand yet in Paul’s day (and presently) Israel as a whole does not believe that Jesus is the Messiah.
The evidence stands against them for the prophets had spoken about God’s mercy left and right (a fact that is overwhelmingly ignored when looking at God in the Old Testament). Speaking about a cast off Israel, God through Hosea says He will take those cast off Israelites and call them His People and they will thus be called living sons of the living God. Speaking about a chastised Israel, Isaiah says that the entire Israelite nation will not be wiped out but there would be a remnant, a small shoot, that will be saved and preserve Israel for God has left them this posterity instead of wiping them out like Sodom and Gomorrah.
So God did in fact show mercy to Israel that He hasn’t wiped them out and He doesn’t intend to wipe them out but currently Israel does not believe because in the way they pursued God’s righteousness.