I'm not surprised that this thread is still going on. There are so many brethren that haven't bothered to study the OT Scriptures along with the NT which has produced a one-sided view in their minds about God's Israel and His Church through Jesus Christ.
At the same time, Jewish traditions also have gotten in the way of many believing Jew's understanding about Christ's Church and how it directly relates to God's Israel also.
Darby's theory of dispensationalism is one of the major factors to blame among Gentile believers, as that doctrine was created to help support his false pre-tribulational rapture theory, trying to keep Christ's raptured Church separate from "left-behind" Israel, and with that theory of separation continuing through Christ's "thousand years" after the tribulation with His Church in Heaven while Israel is setup as a kingdom on the earth for that time.
The name 'Israel' is the new name God gave to Jacob involving the transferred blessing He first gave to Abraham. And that involved the Promise by Faith given through Abraham, which is about The Gospel of Jesus Christ (see Galatians 3). The Gospel is part of God's Birthright Blessing through Abraham, then to Isaac, and then Jacob, and then to Joseph, and then to Joseph's two sons Ephraim and Manasseh. That name Israel cannot be separated from Christ's Salvation of The Gospel, for that is what the name represents.
In Romans 11 Apostle Paul explained that the Gentiles who believe are graffed in, and to not boast against the branches that were broken off (unbelieving Israel) so Salvation could also go to the Gentiles. If the unbelieving branches of Israel that were broken off come to believe on Christ Jesus, then God is able to graff them in again. When Jesus comes, and the unbelievers of Israel see Him, then the majority of them will believe and understand, which is one of the subjects of the Zechariah 12-13 prophecy. Paul said that blindness in part has been put upon unbelieving Israel, but will one day be removed (when Jesus returns), and so all Israel shall be saved.
Rom 11:25-29
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.
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.
KJV