25So that you may not claim to be wiser than you are, brothers and sisters, I want you to understand this mystery: a hardening has come upon part of Israel, until the full number of the Gentiles has come in. 26And so all Israel will be saved; as it is written, "Out of Zion will come the Deliverer; he will banish ungodliness from Jacob."
27"And this is my covenant with them, when I take away their sins." 28As regards the gospel they are enemies of God for your sake; but as regards election they are beloved, for the sake of their ancestors; 29for the gifts and the calling of God are irrevocable. 30Just as you were once disobedient to God but have now received mercy because of their disobedience, 31so they have now been disobedient in order that, by the mercy shown to you, they too may now receive mercy. 32For God has imprisoned all in disobedience so that he may be merciful to all.
33O the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways! 34"For who has known the mind of the Lord? Or who has been his counselor?"
35"Or who has given a gift to him, to receive a gift in return?" 36For from him and through him and to him are all things. To him be the glory forever. Amen.
From Paul's perspective, salvation of people groups unfolds within God's providential history. That is, God's own unfolding plan for humanity includes salvation of nations/people groups. It is from this perspective that Paul declares that "all Israel will be saved." What does this mean?
First, "all Israel" does not mean every single Israelite. It's an expression for a significant or a representative number of Israelites (e.g., Joshua 7:25, 2 Samuel 16:22, Daniel 9;11). Then who is "Israel"? Three possibilities. (1) God saves all his elect people, both Jews and Gentiles -- those who respond to God's grace throughout history. Here "Israel" = church [which includes Jewish and Gentile believers]. (2) God saves all elect Jews as they respond to God's grace throughout history. (3) God will save a significant number of Jews at the end of history.
We are not certain what Paul has in mind by "All Israel will be saved." There is a distinction between Gentile and Israel throughout this passage. If this distinction continues to hold when Paul writes "all Israel," then "Israel" here does not include Gentiles, hence (1) becomes less tenable. There is also, within the larger passage, a sense of historical unfolding, that Gentile believers will reach a certain fullness in number and then (if we translate 'so' as 'then') a significant number Israelites will be saved. If this historical sequence is what Paul has in mind, (2) becomes less likely and (3) becomes more likely.
A larger question we can ask if we consider God's providence and salvation of ethne (people groups): Does God have a timeline for when certain nations/people groups come to salvation in Christ? This semi-rhetorical question has a non-rhetorical answer: Yes! If we share Paul's perspective that God is provident and that God is the primary agent in salvation, then we can only conclude that God indeed has such a timeline. Salvation, if we consider it from another angle, is not "random" or arbitrary. Furthermore, when we examine the history of the church -- the global expansion of Christianity -- we can clearly see this salvific unfolding empirically. Nations/people groups in large numbers come to faith in Christ at certain points in history. Such is the case now! China, Iran, parts of Africa and Latin America are some of the places currently where people are coming to faith in Christ in significant numbers. For this we ought to thank God! And we ought to pray for places where the response to the Gospel has not (yet) been so positive! So, pray for places like Thailand and Japan, parts of the Middle East, Western Europe, and even Korea, whose young people are showing less interest in God. And America.
Let's pray: O Lord, we trust in your providential, unfolding plan for humanity. We thank you that you are in control. We pray for your mercy and salvation to fall upon these areas and people. We pray for the salvation of the Thai people. We pray for Japan and Turkey. We pray for Germany, France, and the UK. We pray for Korea (SK and NK). We pray for U.S.A. We pray for a mighty move of God that will sweep up people into the joy of your salvation! In Jesus' name, Amen.