" 25 I would not that this secret should be hid from you my brethren, lest ye should be wise in your own conceits: that partly blindness is happened in Israel, until the fullness of the gentiles be come in. 26 And so all Israel shall be saved. As it is written, "There shall come out of Zion he that doth deliver, and shall turn away the ungodliness of Jacob. 27 And this is my covenant unto them, when I shall take away their sins." 28 As concerning the gospel, they are enemies for your sake: but as touching the election, they are loved for the fathers' sake."
The Christian Zionist or dispenszationalist interpretation of this is that when all Gentiles God intends to save are saved, then God will save all Israel, meaning all who belong the physical blood line from Abraham.
To the Christian Zionist all Israel - the multitude of Old Covenant Israel - cannot mean that all of the elect, regardless of their DNA, are said to be Israel and are saved.
Christian Zionism separates those of the physical bloodline from all others, called the Gentiles. And Christian Zionism says God has another people called the Church. In the New Testament church is a translation of ekklesia, meaning a meeting, assembly or congregation. There seems to be a confusion in Christian Zionism on whether saved Jews belong to the church, but usually the Christian Zionists just say they too are Israel, but no saved Gentile can be part of Israel, the chosen by the physical bloodline.
It seems that Christian Zionists think that Romans 11: 28 supports their theology shown briefly above.
But Paul in Romans 11: 28 does not explain who "they" are who are enemies for you sakes concerning the Gospel, but concerning election "they" are beloved for the sakes of the Fathers, Abraham, Isaac and Jacob.
He means those of Old Covenant Israel as "they." But how are "they" as the same people both enemies of the Gospel for the sake of Gentile believers, and beloved by the Fathers concerning their election? Paul is talking about two different groups of Old Covenant people, one whose religion makes them enemies of the Gospel and another group who are the remnant and are the elect (Romans 11: 1-5).
Remember that in Romans 9: 6-8 Paul writes about two groups who are both of the physical bloodline, one he calls children of the flesh who are not the children of God and another group the children of the promise who are the seed, that is, the elect group.
But Romans 11: 25-26 has to be kept in a separate compartment in order to prevent other New Testament scriptures from making evident and outstanding in perception different and opposite doctrines.
Remember that the Christian Zionist view that the multitude of Old Covenant Israel is to be saved in Romans 11: 26 depends upon them being recognized by God as being of the chosen physical bloodline. Any New Testament scripture which teaches that the physical bloodline was done away with in the New Covenant undermines Christian Zionism.
"Are ye so unwise, that after ye have begun in the spirit, ye would now end in the flesh?.......... Even as Abraham "believed God, and it was ascribed to him for righteousness." 7 Understand, therefore, that they which are of faith, the same are the children of Abraham. 8 For the scripture saw aforehand, that God would justify the heathen through faith, and therefore showed beforehand glad tidings unto Abraham: "In thee shall all nations be blessed." 9 So then, they which be of faith are blessed with faithful Abraham.............. But Christ hath delivered us from the curse of the law, and was made accursed for us — for it is written, "Cursed is everyone that hangeth on tree" — 14 that the blessing of Abraham might come on the gentiles through Jesus Christ, and that we might receive the promise of the spirit through faith. 1........To Abraham and his seed were the promises made. He saith not, "in the seeds," as in many: But, "in thy seed," as in one, which is Christ. 17 This I say, that the law which began afterward, beyond four hundred and thirty years, doth not disannul the testament, that was confirmed afore of God unto Christ ward, to make the promise of none effect. 18 For if the inheritance come of the law, it cometh not of promise: but God gave it unto Abraham by promise............. For ye are all the sons of God, by the faith which is in Christ Jesus. 27 For all ye that are baptised, have put on Christ. 28 Now is there no Jew, neither gentile, there is neither bond nor free, there is neither man nor woman: but ye are all one thing in Christ Jesus. 29 If ye be Christ's, then are ye Abraham's seed, and heirs by promise." Galatians 3.