In Rom 11:25, Paul says to the non-Jewish followers of Jesus in Rome, that they must not be wise in their own sight. He says this in connection with his previous imagery of the olive-tree; Jews who do not believe in Jesus have been broken of, but if they come to faith in Christ, they will be grafted into the tree again and participate in salvation. The non-Jewish believers must not consider themselves as higher than the unbelieving Jews, for God still desires that these Jews come to faith. Read Rom 11:25-26:
I want you to understand this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in. And thus all Israel shall be saved.‘A partial hardening of Israel’ - Paul spoke about this previously, in Rom 11:7-10. There he explained that the elect part of Israel had become partaker in salvation, but that the rest was hardened. I think we should not differentiate between the hardening mentioned in Rom 11:7-10 and the hardening Paul mentions in Rom 11:25. He speaks about the same matter.
In Rom 11:11, Paul writes that this hardening of Israel ensured that salvation could come to the nations. I think Paul says the same thing in other words in Rom 11:26, when he speaks of the fullness of the nations that enter. We must notice the parallelism in the passages Rom 11:7-10 and 11:25-26.
So when Paul speaks about the fact that he wants to make hardened Jews jealous, in order to save some (Rom 11:11b-15), then that seems to me to be the logical parallel to ‘thus all Israel shall be saved.’ (Rom 11:26)
From the beginning of the letter, the question of the Jewish believers in Rome was clear: ‘Paul, please explain, God has promised great things to Israel. Would he not save Israel with the coming of the Messiah?’ Paul has now given his answer. Only a small part of Israel has come to faith; that is how the Gospel could go to the nations. Now is the time for the non-Jewish followers of Jesus to preach the Gospel to the Jews.
This is what Paul discusses in Rom 11; Jews have been hardened; pagans come to faith, and must bring the Gospel to the Jews so that they will come to faith. Paul speaks of himself and his role, not of a distant end of times scenario.
In Rom 11:30-32 Paul repeats the same concept: Jews are hardened, but people from the nations have come to faith, so that they now proclaim the Gospel and Jews come to faith. Paul explicitly uses the word now: ‘so that now they receive mercy’. He is not speaking about a distant end of times, but about his own task, and the task of the congregation in Rome. Seeing this, it seems obvious that the words of Rom 11:26 must be read in this context. A part of Israel has been hardened, people form other nations come to faith, and they must now proclaim the Gospel to Israel. This is not eschatology, but missiology for Paul. He discusses the task of the Church.
Israel has been partially hardened, Paul says in Rom 11:26. That does not need further discussion. We have seen in the whole letter of Paul that this is a fact that he preaches. Most Jews have not accepted Jesus Christ as Lord. This partial hardening has to do with a mystery, says Paul: The plans of God have not gone wrong by Israel’s unbelief, but salvation could come to the nations in this manner. Many people there came to faith. The hardening of Israel is until the fullness of the nations has gone in. I have often heard it said that this refers to the total number of pagans coming to faith throughout the centuries. To me this seems completely unjustified, exactly because Paul places his whole discussion in the context of missiology (the testimony that must be given to Israel in his own time), not eschatology, as we have seen.
The concept of fullness of the nations occurs in the Old Testament in Genesis 48:19. Jacob blessed Ephraim with the words that his posterity would be a fullness of nations. In the LXX we read about this pleetos ethoon; Pasul uses the related words pleeroma toon ethnoon. Does Paul refer to these words of Jacob? That would fit very well in the context, because Paul makes clear in his whole letter that whosoever believes in Jesus Christ, whether he is Jewish or not, may consider himself posterity of Abraham.
‘When the fullness of nations goes in’ refers to the non-Jews who are coming to faith, and who thereby enter into the Kingdom of God. The concept of fullness does, in any case, not refer to all, just as the blessing of Jacob to Ephraim does not mean that Ephraim will be the forefather of all nations. In the immediate context, in Rom 11:11, the word fullness is also used in regard to Israel. There it refers to the opposite of the fall and unbelief of Israel. In this context the term has nothing to do with a complete number or something like that either.
‘Thus (Greek: houtoos) all Israel shall be saved.’ The word thus does not mean ‘after this’ or something like that. Paul is not defining a specific time, but the issue of cause and effect. Paul explains in what manner Israel can be saved.
‘All (Greek: pas) Israel’: In the whole letter, Paul always means numerical totality with this word ‘all’. We would be foolish to not interpret the word ‘all’ in the same manner in Rom 11:26. Paul has clarified in his letter that all who believe in Christ shall be saved. If the Jews in the Church in Rome wonder about the promises of God to save all Jews, the answer of Paul is clear. God does stick to his promises. In order for all Israel to be saved, all Jews have to believe in Jesus Christ. Paul does not give any guarantee in this verse that all of Israel will be saved; he explain in what manner all of Israel can be saved.
And that term ‘saved’, or ‘salvation’? Paul has said enough about this in his letter. I refer to Rom 8, where Paul clarifies what salvation means for all followers of Christ, both for Jews and for non-Jews. Never does Paul infer that there is a special route to salvation for Jews. God wants to show mercy to all people, including the Jews (Rom 11:31-32).
To the believers from the nations, mercy has been shown, and God wants to use them, to ensure that unbelieving Jews would now (now, that is, around 55-56 AD) find mercy. Paul quotes two verses form Isa 59:20 and Jer 31:33-34. It is instructive to look at those verses in their context. Isaiah says that the redeemer will come from Zion for those who convert from their transgressions. And Jeremiah says that God writes his laws in the hearts of those whose sins are forgiven. Paul has underlined in his whole letter that this is how God offers forgiveness: when people come to faith in Christ. There is no shortcut for anyone.
So we see that Paul, in regard to the question about salvation for Israel, answers with a task for the church in Rome. ‘Yes’, Paul says, ‘God wants all Israel to be saved. But in order for Israel to be saved, it has to accept the Gospel. There is no guarantee that all Jews will ever do so, but our task as a church is to present the Gospel to them. Only thus, in that manner, all Israel shall be saved. There is no other way.’