Some argue Israel is now the church — almost treating Israel like a metaphor for the church. Often (and this is my understanding of their position) they say there is no future hope for Israel’s restoration. This view however is hard to explain given biblical data. God says in Romans 11:25-29,
For I do not want you, brethren, to be uninformed of this mystery — so that you will not be wise in your own estimation — that a partial hardening has happened to Israel until the fulness of the Gentiles has come in; and so all Israel will be saved; just as it is written, ‘The deliverer will come from Zion, He will remove ungodliness from Jacob.’ ‘This is my covenant with them, When I take away their sins.’ From the standpoint of the gospel they are enemies for your sake, but from the standpoint of God’s choice they are beloved for the sake of the fathers; for the gifts and the calling of God are irrevocable.”
Now, if Israel is just a synonym for the church, Romans 11:25-29 communicates there is a partial hardening of the church until the fulness of the Gentiles has come in. This does not make sense, “A partial hardening has happened to the church until the fulness of the Gentiles has come in; and so all the church will be saved? This view seems to build upon a presupposition stating, “The church is the people of God” and “Israel is the people of God.” But, the problem with this view, whether the presupposition is accurate or not, exists when we try to remain faithful to the meaning of the Scripture.
The text highlights ethnic distinctions indicated by the use of “Gentile” and “Israel.” If these are merely metaphors for believer / unbeliever, the text does not make sense either. For there is “a partial hardening to believers until the fullness of unbelievers has come in so all believers will be saved.” In other words, God is hardening believers against what? The Gospel? unbelievers? God’s plan? What? Usually this metaphor means people are hardened against the Lord, His work, and refuse to believe the Lord. The above interpretations do not make sense nor do they accurately convey the meaning of Romans 11.
The best answer, justified by the text, interprets Israel as the ethnic nation Israel. So, there is a partial hardening of the nation Israel until the fulness of the Gentiles has come in; and so all the ethnic nation Israel will be saved. Verse 28 and 29 communicate, Right now they are enemies of the Gospel. Yet from God’s point of view they are beloved chosen and “the calling of God are irrevocable.” God has called Israel. He tells us His calling is irrevocable.
The only way to do justice to Romans 11:25-29 is to understand Israel as the nation Israel and not the church. One clarification needs to be made. Right now there is a partial hardening. Right now God still saves Israelites and makes them a part of His church. Yet there is a future day when all Israel will be saved. In fact, Zechariah says, “I will pour out on the house of David and on the inhabitants of Jerusalem, the Spirit of grace and of supplication, so that they will look on Me whom they have pierced; and they will mourn for Him, as one mourns for an only son, and they will weep bitterly over Him like the bitter weeping over a firstborn” (12:10)
“Is there a future hope for ethnic Israel? Paul’s answer was yes. And the presence of a believing remnant was proof.” 
Kim Riddlebarger, A Case for Amillennialism, 2003, 194.