Let's take a look at the verse:
Rom 11:26,
And in This Way, All Israel Will Be Saved: The Meaning of Romans 11.26
Lest you be wise in your own conceits, 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 in this way all Israel will be saved. Romans 11.25-26
Paul wants the reader to understand the mystery of the partial hardening of Israel and the hope that
all Israel will be saved. Unfortunately, although Paul was intending to make the mystery clear to the reader, that sentence has proved to be most puzzling for those who are trying to understand who is the Israel Paul refers to. There are several ways to interpret the meaning of Romans 11:26:
The Elect. Both Jew and Gentile; the Church of individual Christian believers"
In the context of all Paul’s teachings:
all Israel of Romans 11.26 refers to all of the elect, both Jew and Gentile. In other words, the church has become the Israel of God. Indeed, Paul redefined basic terms of Judaism several times in his writings. In Galatians 6.16, Paul described
those in Christ as the Israel of God. He redefined circumcision, Philippians 3.3, Colossians 2.11-12, and what it means to be a descendant of Abraham.
In Romans 9-11, he wrote that not all who descended from Israel belong to Israel, Romans 9.6 and that everyone who calls upon the name of the Lord shall be saved, with no distinction between Jew and Greek. Galatians 3:29
Beginning with Romans 11.13, Paul warned the Gentiles not to be
arrogant towards the branches, meaning that the Gentile believers were not to think of themselves as more loved by God since most Jews have rejected the Messiah. After all, Gentiles were only grafted in by God’s grace and mercy. But non-ethnic people ARE grafted into the Israel of God, by reason of their belief in God and their faith in Him.
Ethnic Israel. The Jewish people, plus the 10 tribes still scattered among the nations:
Another way that some have understood the “all Israel” of Romans 11.26 is that Paul was writing of the ethnic Jewish nation of Israel . In other words, Paul meant that at some point in time in the future, after the fullness of the Gentiles had come into the Kingdom of God, the ethnic descendants of Jacob would be saved. It is hardly likely that:
all Israel means every descendant of Jacob that had ever lived or those Israelites who will be alive at the time when the fullness of the Gentiles becomes complete. Regardless, the basic tenet of this view is that after the full number of the elect Gentiles had come to faith in Christ, there would be a mass conversion of Israel to faith in Christ. Most think that this would happen just prior to or at the moment of Christ’s Return, when:
the Deliverer will come from Zion. At this point, the Messiah would
banish ungodliness from Jacob, which some take to mean that God would remove the hardening upon Israel. Romans 11.25
There are two major difficulties with this view. The first problem deals with the proper interpretation of two small Greek words. The first word of interest is the Greek word ούτώς in Romans 11.26. The basic meaning of the word is
in this manner (Thayer’s Greek Definitions) and usually has a modal sense: dealing with the manner of Israel’s salvation, and never a temporal sense: dealing with the timing of Israel’s salvation.
The NIV interprets Romans 11.26 to read,
And so, all Israel will be saved, which could be read:
and after the fullness of the Gentiles has come in, then all Israel will be saved, but this is not the best interpretation of the text. The ESV captures it better by reading:
And in this way, all Israel will be saved. The “
in this way” has already been clearly explained by Paul in Romans 10:8-17…
faith comes by hearing and hearing by the word of Christ and there is no distinction between Jew and Greek as to the manner of salvation.
The second Greek word of interest is άχρι in Romans 11.25. The basic meaning is “until” and is essentially terminative in its significance, implying the end of something. But the context alone determines whether the emphasis is upon what happens after the end of something or upon the end itself. For example, in 1 Corinthians 11.26, Paul instructed the church about the Lord’s Supper saying:
For as often as you eat this bread and drink the cup, you proclaim the Lord’s death until he comes.
The emphasis was not that the church would cease to celebrate the Supper after the Lord’s return but that the Lord’s Return would terminate the celebration of the Supper. Another example is 1 Corinthians 15.25 where Paul wrote
that Christ must reign until he has put all his enemies under his feet. The point was not that there would come a time when Christ would no longer reign but that He would continue to reign until the last enemy was conquered.
It seems that the entire idea of a future mass conversion of Israel at some point in history’s future at the return of Christ depends upon these two words being interpreted in a way that is contrary to the context.
But the second major difficulty is that it seems to imply, or at least many who hold to this interpretation insist upon, that the way unto salvation for Israel will be different than the way of salvation for the Gentiles. Some have suggested that the conversion of all of Israel will happen through a direct revelation of Christ prior to the Second Coming, much like what happened to Paul on the road to Damascus. But this seems to contradict the point of Romans 10-11, that there is no distinction between Jew and Greek and that faith comes by hearing and hearing by the Word of the Gospel. It would seem that Romans 10:6 would be rendered meaningless, too.
Others have suggested that there is a two track way to salvation, one for the Gentiles and one for the Jews. In other words, while the Gentiles are being saved by grace through faith, the Jews will be saved by their faithfulness to the Sinai covenant. But this contradicts the entire teaching of the book of Romans. How could Paul write:
by works of the law no human being will be justified in His sight. Romans 3.20, and then imply that the Jews will be saved if they return to being faithful to the law? Furthermore, if there are two ways to enter the Kingdom of God, then Paul’s analogy of the olive tree, makes no sense.
Others have suggested that the future mass conversion of the Jewish people will indeed be the mystery that Paul wrote about. At some point in the future, the hardening will be removed and the Jews, as a whole but not necessarily every single Jewish person, will believe in Jesus and confess Him as Savior and Lord. While this is a wonderful thought, and would indeed be a mystery, it does not fit the plain reading of the text.
Despite the interpretation of “until” and “so” of Romans 11.25-26 that was mentioned above, it should be noted that Paul has been speaking in the present tense throughout Romans 11. He wrote of the remnant chosen by grace
at this present time. Romans 11.5 He was hopeful that his ministry might make his fellow Jews jealous in order to save some of them, Romans 11.13-14 He also was hopeful that that those who were disobedient may “now” receive mercy. Romans 11.30-31
It seems that Paul was in anguish for his kinsmen according to the flesh to be saved, to confess with their mouth that Jesus is Lord. If he were confident that at some point in the future “
all Israel would be saved,” then why be in anguish? Indeed, he knew that
not all obeyed the gospel. Romans 10.16
In addition, if Paul did write about a future conversion of all of Israel, then this would be the only place in the New Testament where this last days idea is introduced. Jesus did not speak of it in Matthew 24, nor did Paul write of it in 1 Thessalonians 2.14-16 where he wrote of God’s wrath coming upon the disbelieving Jews until the end. It is missing from the vision given to John in the book of Revelation.
There has always been, and continues to be, a remnant chosen by grace among the Jews who believe that Jesus is the Christ, that God raised Him from the dead, and who confess Him as Lord.
But they are only a small portion of the entire Christian Israel of God.
Therefore it is as Revelation 5:9-10 says:
people from every tribe, race, nation and language are made unto God His rulers and priests, His overcomers on earth, the Israelites of God. ALL the faithful Christian people. 
