The apostle Paul stated that ‘all Israel would be saved.’ (Rom. 11:26) Did he mean that at some point all Jews would be converted to Christianity?

 
No, that is not what Paul was saying. As a nation, the natural descendants of Abraham rejected Jesus as the Messiah. And in the years following Jesus’ death, it became clear that there would be no wholesale conversion of Jews to Christianity. Still, Paul’s statement that ‘all Israel would be saved’ was true. In what way?
 
Jesus said to the Jewish religious leaders of his day: “The kingdom of God will be taken from you and be given to a nation producing its fruits.” (Matt. 21:43) Because the nation of Israel as a whole rejected Jesus, Jehovah would turn his attention to a new nation, a spiritual one. Paul called this nation “the Israel of God.”—Gal. 6:16.
 
Other passages in the Christian Greek Scriptures establish that “the Israel of God” is made up of 144,000 spirit-anointed Christians. (Rom. 8:15-17; Rev. 7:4) That this group would include non-Jews is confirmed by Revelation 5:9, 10, which shows that anointed Christians come “out of every tribe and tongue and people and nation.” The members of spiritual Israel were specially selected to be “a kingdom and priests . . . , and they are to rule as kings over the earth.” Although Jehovah rejected Israel as a chosen nation, individuals could become reconciled to him. That was the case with the apostles and many other early Christians. Of course, such Jews, like all other humans, had to be bought with the blood of Jesus Christ.—1 Tim. 2:5, 6; Heb. 2:9; 1 Pet. 1:17-19.
 
The fact that the majority of fleshly Jews in the first century lost out on the opportunity to become corulers with Jesus did not thwart God’s purpose. This could never be, for Jehovah stated through his prophet: “So my word that goes forth from my mouth will prove to be. It will not return to me without results, but it will certainly do that in which I have delighted, and it will have certain success in that for which I have sent it.”—Isa. 55:11.
 
That is true with regard to God’s purpose to install 144,000 corulers alongside his Son in heaven. The Bible makes clear that God would anoint a complete number of 144,000. Not one would be missing!—Rev. 14:1-5.
 
Thus, when Paul wrote that ‘all Israel would be saved,’ he was not foretelling a mass conversion of Jews to Christianity. Rather, he meant that God’s purpose to have 144,000 spiritual Israelites ruling with His Son, Jesus Christ, in heaven would be fulfilled. In God’s due time, the complete number—“all Israel”—would be in a saved condition, eventually ruling as kings and priests in the Messianic Kingdom.—Eph. 2:8.