READ: Rom. 11:23–29: … God is able to graft them in again … a partial hardening has come upon Israel until the fullness of the Gentiles has come in. And so all Israel will be saved …
The “mystery” of which Paul speaks in verse 25 is something that had been hidden but has now been made known through divine revelation. It concerns God’s redemptive plan by which He fulfills His promises to Israel. There will not be a total hardening of Israel, but a partial one: throughout history, natural branches are grafted in again.
This hardening in unbelief takes place over time, from Pentecost until the moment when the full number of the Gentiles has come in—when the last day dawns. In that way all true Israel will be saved. This revelation must remove every form of arrogance among believing Gentiles.
It is therefore incorrect to conclude that the hardening of the Jews will at some future point be entirely removed, followed by a mass conversion shortly before Christ’s return. The partial hardening is not temporary in the sense of being completely reversed at one historical moment. It continues until the full number of all the elect has entered in: of the Gentiles (v.25) and of the Jews (v.26)—that is, all true Israel, the remnant of all ages (cf. v.8).
What does “has come in” mean? Does it refer to entering the kingdom of heaven? Or to being grafted into the olive tree described in verses 17–24—the one catholic church composed of Jews and Gentiles? Most likely it refers to coming to true faith. When the last elect person is brought to faith, the return of Christ will take place. Then the number of believing Jews will also be complete.
In interpreting this passage, other Scriptural data must be considered: in the new dispensation there is no separate covenant people alongside the one church—there is one flock; the dividing wall has been broken down (Eph. 2:14).
Moreover, all promises are fulfilled in Christ (2 Cor. 1:20), including that of the promised land. The return of Christ comes like a thief in the night.
In all this, one truth remains firm: God remains faithful.
Can Israel be called a “brother nation” of the church?
Sing: Ps. 87:3,4