The name "Israel" pertains to human beings - the elect seed of Abraham, and the word "temple" pertains to the house of God:
Israel: The elect seed of Abraham (human beings).
Temple of God: The house of God (a.k.a the church).
THE ELECT SEED IN THE NEW COVENANT
Paul wrote a lot about this.
In Romans 9:6-7 Paul began talking about the descendants of Israel, saying that not all the descendants of Abraham are children of Abraham, nor are they "Israel" merely because they are descendants of Israel.
This is the same subject Paul continues with all the way through to the close of chapter 11. Therefore whatever Paul says in Romans 11 cannot be divorced from Romans chapter 9.
(Note that chapter divisions were added to the Bible in circa 1227 AD, and verse numbers were added in the 16th century. Chapter 11 is still talking about the same subject Paul introduced in chapter 9).
In Romans 11:23-24 Paul said that the descendants (plural) of Israel who are broken off through unbelief will be blessed in Christ and grafted into God's elect people again IF they do not continue in unbelief.
Paul's choice of words is important, because he did not say when they turn away from unbelief, but IF they turn from unbelief.
Turning away from unbelief to faith in Christ has been happening in the cases of individual Jews ever since the Deliverer came out of Zion and made a new covenant with them IN THE DAY HE TOOK AWAY THEIR SINS (Romans 11:26-27).
As Paul says:
Romans 9:27: "Isaiah also crieth concerning Israel, Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved."
Romans 11:5: "Even so then at this present time also there is a remnant according to the election of grace."
Romans 11:26a: "And so all Israel shall be saved."
Paul has already defined ALL ISRAEL:
Romans 9:24-26: "That is, us, whom he hath called, not of the Jews only, but also of the Gentiles (As he saith also in Hosea, I will call them my people, which were not my people; and her beloved, which was not beloved, and it shall come to pass, that in the place where it was said unto them, Ye are not my people; there shall they be called the children of the living God)."
Romans 11:26b-27: "As it is written, There shall come out of Zion the Deliverer, and shall turn away ungodliness from Jacob: For this is my covenant unto them, when I shall take away their sins."
THE TEMPLE OF THE NEW COVENANT
Before Christ died and the veil in the Old Covenant temple was torn in two, Israel had a temple, and the worship of God revolved around it.
Since the coming down of the Holy Spirit upon the believers (the church) congregated in Jerusalem on the Day of Pentecost, the congregation of the citizens of the elect remnant who are in Christ, together with the Gentile believers who are in Christ, are the "living stones" of the New Covenant Temple (the church).
------------------------------------------------------------------------------------------------
Passages such as 1 Peter 2:5 and Ephesians 2:18-22 make it abundantly clear that the New Covenant Temple (a.k.a the church) is not divorced by Apostolic doctrine from the (elect) citizens of Israel.
------------------------------------------------------------------------------------------------
The term: "Replacement Theology"; and the statement: "The church did not 'replace' Israel" are both meaningless and based on a logical fallacy, because the church would not exist, were it not for the remnant of Israel:
Israel: The elect seed of Abraham (human beings).
Temple of God: The house of God (a.k.a the church).
Romans 11:28-29: "As concerning the gospel, they (those who are broken off) are enemies for your sakes: but as touching the election, they (the remnant) are beloved for the fathers’ sakes. For the gifts and calling of God are without repentance."
In Romans 11:28-29 (above) Paul is still making the same distinction he makes in Romans 11:1-7 between (a) the remnant of Israel who have not been cast off; and (b) the descendants who have been broken off:
Paul is reiterating not only the fact that God has not cast away His people (Israel) because there remains a remnant (Romans 11:1-7), but also the fact that it is due to the descendants of Israel who are broken off through (their) unbelief) that salvation came to the Gentiles (Romans 11:11 & 17),
and Paul is also reiterating what he said in Romans 9:6-7 (where he began talking about this subject): that not all the descendants of Abraham are children of Abraham, nor are they "Israel" merely because they are descendants of Israel.
----------------------------------------------------------------------------------------------
Paul is not saying in Romans 11:28 that the descendants of Israel who have been broken off (through their own) unbelief are nevertheless "beloved for the sake of the fathers" (Abraham, Isaac and Jacob / Israel): He is saying that the remnant are beloved for the sake of the fathers, and the rest are enemies of the good news / gospel (because they do not believe) - and this has benefited the Gentiles, because salvation has come to the Gentiles through their unbelief.
----------------------------------------------------------------------------------------------
Romans 11:12 & 25: Paul states that for as long as Gentiles are coming into the same spiritual fullness [G4138 pleroma] (verse 25) of the remnant of Israel (verse 12), the fullness [G4138 pleroma] experienced by every Jew who repents of unbelief (verses 12 & 23) is as life from the dead (verse 15), and results in even greater riches for the same Gentiles.
In the day He took away their sins (Romans 11:27), the Deliverer who came out of Zion made a covenant with those who believe (Romans 11:26-27).
In Romans 9:22-33 "ALL ISRAEL" had already been defined by Paul as the remnant of Israel + believing Gentiles "grafted in" among them" who are ALL saved in this way, and shall be saved in this way (compare Romans 9:22-33 and Romans 11:26-27).
--- ---
