Romans 11:26 plainly says, “All Israel will be saved.” The question that arises is “What is meant by Israel?” Is the future “Israel” literal or figurative (i.e., referring to the ethnic Jews or referring to the Church)? Those who take a literal approach to the promises of the Old Testament believe that the physical descendants of Abraham, Isaac, and Jacob will be restored to a right relationship with God and receive the fulfillment of the covenants. Those who advocate replacement theology basically affirm that the Church has completely replaced Israel and will inherit God’s promises to Israel; the covenants, then, will be fulfilled only in a spiritual sense. In other words, replacement theology teaches that Israel will not inherit the actual land of Palestine; the Church is the “new Israel,” and ethnic Israel is forever excluded from the promises—the Jews will not inherit the Promised Land as Jews per se.
The literal approach seems better. The passages that speak of future Israel are difficult to view as figurative for the Church. The classic text (Romans 11:16–24) depicts Israel as distinct from the Church: the “natural branches” are the Jews, and the “wild branches” are the Gentiles. The “olive tree” is the collective people of God. The “natural branches” (Jews) are “cut off” the tree in unbelief, and the “wild branches” (believing Gentiles) are grafted in. This has the effect of making the Jews “jealous” and then drawing them to faith in Christ, so they might be “grafted in” again and receive their promised inheritance. The “natural branches” are still distinct from the “wild branches,” so that God’s covenant with His people is literally fulfilled. Romans 11:25–29, citing Isaiah 59:20–21; 27:9; Jeremiah 31:33–34, says:
In this way all Israel will be saved. As it is written: “The deliverer will come from Zion; he will turn godlessness away from Jacob. And this is my covenant with them when I take away their sins.” As far as the gospel is concerned, they are enemies for your sake; but as far as election is concerned, they are loved on account of the patriarchs, for God’s gifts and his call are irrevocable.
Here, Paul emphasizes the “irrevocable” nature of Israel’s calling as a nation. Isaiah predicted that a “remnant” of Israel would one day “be called the Holy People, the Redeemed of the LORD” (Isaiah 62:12). Paul speaks of the “full inclusion” of Israel in the future (Romans 11:12). Regardless of Israel’s current state of unbelief, a future remnant will in fact repent and fulfill their calling to establish righteousness by faith (Romans 10:1–8; 11:5). This conversion will fulfill Moses’ prediction of Israel’s permanent restoration to the land (Deuteronomy 30:1–10). God’s larger redemptive plan involves both Jews and Gentiles. When Paul says Israel will be “saved,” he means their deliverance to this physical inheritance as integral to God’s ultimate plan (Romans 11:30–36).
So how will “all Israel be saved” and restored in the land? The details of this deliverance are filled out in passages such as Zechariah 8–14 and Revelation 7–19, which speak of end-times Israel at Christ’s return. The key verse describing the coming to faith of the future remnant of Israel is Zechariah 12:10, “I will pour out on the house of David and the inhabitants of Jerusalem a spirit of grace and supplication. They will look on me, the one they have pierced, and they will mourn for him as one mourns for an only child, and grieve bitterly for him as one grieves for a firstborn son.” This occurs during the tribulation prophesied in Daniel 9:24–27. The apostle John references this event in Revelation 1:7. The faithful remnant of Israel is epitomized in Revelation 7:1–8 and 11:1–12. These faithful ones the Lord will save and bring back to Jerusalem “in truth and righteousness” (Zechariah 8:7–8, NASB).
The tribulation period will feature unprecedented apostasy in Israel for 3½ years, with a “second exodus” arranged by God to protect the faithful remnant from Satan (Revelation 11–12) just as in the first Exodus. Isaiah predicted this as well: “In that day the Lord will reach out his hand a second time to reclaim the surviving remnant of his people” (Isaiah 11:11). The gospel will be preached to all the world, and Christ will return to meet the faithful remnant (Revelation 14) and destroy the armies gathered against Him in rebellion (Revelation 19). The apostates left in Jerusalem will be purged, and the remnant set apart forever as God’s holy people (Zechariah 13:8–14:21). Isaiah 12 is their song of deliverance: Zion will rule over all the nations defeated under the banner of Messiah the King, and Israel’s “salvation” is the wholeness and peace she will enjoy during the millennial reign of Christ.
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.