The question and answer: “Hath God cast away his people?… God hath not cast away his people which he foreknew” (11:1–2) are very important.
Just as God has not cast away His elect, foreknown covenant nation even though her history was full of sin and unbelief, so God will not cast away an individual believer whom He has foreknown (cf. 8:29).
Future conduct does not nullify God’s unconditional promises and gifts. Even in the midst of this time of spiritual blessing upon Gentile peoples, there is a believing Jewish “remnant according to the election of grace” (11:1, 5).
God sovereignly used the spiritual blindness of national Israel to accomplish the blessing of Gentiles (11:11), but one day Israel will again occupy the central position in God’s redemptive program for the world (natural branches to be grafted back into the olive tree).
The blindness of Israel is only partial (some Jews today are being saved) and temporary (until God’s program for the church is completed; cf. 11:25). Then all Israel will be saved.
In practice, the Jews of that generation were enemies, but in position, they were elect and beloved. Paul concluded: “For the gifts and calling of God are without repentance” (11:29).
That means the eternal gift of salvation will never be taken back by God even though a believer may commit future sin. It also means that God will totally complete His program with Israel in spite of her present unfaithfulness.
Paul ended this discourse on Israel by praising the wisdom of God for formulating such a gracious, intricate plan of redemption (11:33–36).
Robert G. Gromacki, New Testament Survey (Grand Rapids, MI: Baker Academic, 1974), 193–194.