The "all Israel" is spiritual Israel, the Israel/people of God, not the nation and Jews of the earthly Israel.
I'm not so sure about that, Rogerg. "Spiritual Israel" doesn't seem to fit the context of Rom 9-11. Here's why I say this: Paul in 9:6-8 defines who the
true Israel is. It isn't the children (descendants) of Abraham according to the flesh; but rather it's the "children of promise". Paul is clearly making a sharp distinction between two groups of Jews. The real Jew in God's eyes are the "children of promise" according to election! And Paul proves this by citing five historical examples of God's election. Issac and Jacob were God's chosen ones, whereas Ishmael and Esau were not. And, of course, Pharaoh was also elected unto reprobation by God, as were Ishmael and Esau.
Having said that, doesn't negate the fact Gentile believers are also spiritual children of Abraham according to what Paul wrote earlier in Romans 4, etc. But Paul's focus in Rom 9-11 is mostly on the Jews. He's explaining to his audience (believing Gentiles) how and why God expanded his redemptive plan to now include God's elect throughout the world. And it's important for the spiritual safety of his original audience that they understand what role national Israel played in the past, in the present and how God's plan will play out to the end of the age, and what role the Gentile believers will play and what their attitude toward Jews should be. This is why he makes such a huge point of explaining
how God's word and his plan did not fail and he has not rejected his people either (9:6; 11:1). Even though things currently look dismal and perhaps even hopeless for national Israel (since they rejected their Messiah and are persecuting God's people), God still has his Jewish remnant that he was saving during Paul's day, has been saving all these centuries and will continue to save to the last day -- this remnant being the "children of promise" -- the true Israel. Therefore, all [true] Israel will be saved come the end of the age. It can't be national Israel since the vast majority of Jews since the first century have rejected and still reject their Messiah. So these who have been rejecting Jesus all these centuries cannot comprise all [true] Israel. The true Israel (true Jews) can only be the "children of promise" remnant. And I think Paul reinforces this idea again in 11:1-2.
"God did not reject his people whom He foreknew." And we we must remember: God has been saving a Jewish remnant for nearly 2,000 years now. This is why cannot be referring to national Israel. God has not been saving every single Jew born since the first century. He's only been saving those whom he foreknew in eternity past. But nonetheless..."all" (again used in the limited sense) Israel will be saved.
Anyhow, this is how I understand "all Israel will be saved". And I stand to be corrected if you see any holes in what I have just stated.