This coming Lord's Day, we are scheduled to finish the first passage of Romans 11, looking especially at verses 2-10. It is important to keep in mind that ultimately, the question in our passage related to Israel's current unbelief, is most important because of the implications on the character of God. If God has foreknown Israel (and He has--Rom 11:2; Amos 3:2), and they (the vast majority of them) have rejected the Messiah, how do we reconcile that with God's sovereignty, particularly related to our security? In Romans 9-11, Paul is explaining how Israel's current unbelief is not inconsistent with God's purposes in His creation. If Israel's unbelief were to prove permanent, then there would indeed by an irreconcilable problem, because God has promised in the Abrahamic, Davidic, and New Covenants that He would save Israel.
To help remember the big picture of Paul's flow of thought/logic in Romans 9-11, I am including the 7 main arguments here as summarized by James Montgomery Boice in his commentary on Romans, pages 1288-9. He was the long-time pastor at 10th Presbyterian Church in Philadelphia, PA.:
God's historical purpose toward the Jewish nation has not failed, because . . .
1. All whom God has elected to salvation are or will be saved (Rom 9:6-24).
2. God had previously revealed that not all Israel would be saved and that some Gentiles would be (9:25-29).
3. The failure of the Jews to believe was their own fault, not God's (9:30-10:21).
4. Some Jews (Paul himself was an example) have believed and have been saved (11:1).
5. It has always been the case that even in the worst of times, a remnant has been saved (11:2-10).
6. The salvation of the Gentiles, which is now occurring, is meant to arouse Israel to envy and thus be the means of saving some of them (11:11-24).
7. In the end all Israel will be saved, and thus God will fulfill His promises to Israel nationally (11:25-32).
It may help to read again some New Covenant passages from the OT books: Deut 30:5-6; Jer 31:31-40; 32:26-44; Ez 36:22-38; and also Hosea 3:4-5, and Zechariah 8:20-23; 14:1-21.
Israel cannot continue in unbelief, because God has chosen them for salvation and to be a witness to the world of His glory! According to Rom 11, that is still future, but also certain!
Sword School this week will be over questions 67, 68, and 69.
Soli Deo Gloria!