In order to fulfill the promises made to them [to Israel].
And here (among other passages):
25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in [G1525 - eiselthe / eiserchomai].
[the "fulness of the Gentiles" being a distinct phrase and meaning from "the TIMES of the Gentiles" ('Gentile domination over Israel' reflected in Neb's 'statue/image' dream, with Neb as 'head of gold' and which started in 606bc and ends at end of trib, per Rev11:1)]
26 And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
27 For this is my covenant unto them, when I shall take away their sins.
28 As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the fathers' sakes.
29 For the gifts and calling of God are without repentance [/irrevocable].
[the section of Romans 9-11 being about "nations": "Israel [singular nation]" and "the Gentiles [plural nations]"]
The reformation has come. The use of Jewish flesh as types and shadows in various historically true parables that hid the spiritual meaning has come to a end.
Salvation has nothing to do with one nation apposed to another. Or flesh and blood, against flesh and blood. The Jew were used to represent both belief and unbelief to the world. Just as the unclean and clean animal used in the same way in ceremonial laws. Laws that pertained to ceremonies to point ahead .
The word Israel has a meaning attached to it. Israel does not mean Jew. It cannot mean whatever a person decides it to. the meaning must be searched out.
Its simply a term used to represent one who has had a encounter with God and has overcome .which all could describe Christianity .
The reason Jacob's name was changed. Not all born again Israel is Israel. Just as the eternity of difference between a inward born again Jew and one that has Jewish flesh .Same kind of flesh as a gentile (corrupted).
When the reformation came have fulfilled all the promises to the Jewish nation to be used in the temporal way . The Jews lost their temporal identity .It clearly became no longer Jew and gentile. (no need)
The all Israel shall be saved is not in respect to a outward Jew but the whole body, as Christ's chaste virgin bride, the church. .
"
Fulness of the Gentiles now that the reformation has come includes members from any nation . A outward Jew is no less considered a gentile ( pagan) today than any other nation .
A terrible tribulation one like never before or ever again for a outward Jew. They have no false hiding place from God. They return to their gentile roots . Abraham's mother was a Amorite and father a Hittite.