I'm quoting Paul, not adding or taking away, so maybe you ought to read it again, and that without adding men's doctrines to it...
Rom 11:25-32
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.'
Of course that means once God removes their blindness HE put upon them for this world, they still must choose Christ Jesus. Paul above is affirming they will... believe on Jesus in that future time with how he quoted from Isaiah. It's because God did promise to save His chosen of Israel; the New Covenant did not change nor eliminate that promise to them.
Apparently, one of the things you struggle with is God's election, His choosing. Do you not remember what Saul, who was a Pharisee, what he was doing on the road to Damascus when Jesus struck him down and converted him? Just when did Paul choose Christ there? He didn't, Jesus chose Paul, like He said in Acts 9. When a direct intervention from The LORD like that happens, it points to God's ownership, like shown in John 17. It shows God already owned Saul, which is how He could directly intervene with converting Saul.
So who are we to say that God won't directly intervene with those Jews He blinded in converting them when Lord Jesus appears? If you've missed it, the fact that He already has divinely intervened with spiritually blinding them away from The Gospel already shows His ownership of them, which is what Paul is also pointing out here...
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.
In other words, God already owns them, He chose them, and He made certain promises to them that He will keep, regardless of what they may want, and regardless of how we may think.
30 For as ye in times past have not believed God, yet have now obtained mercy through their unbelief:
31 Even so have these also now not believed, that through your mercy they also may obtain mercy.
32 For God hath concluded them all in unbelief, that he might have mercy upon all.
KJV
Just as in times past, the Gentiles were without God and His covenants. Yet through their unbelief, we Gentiles have obtained mercy, and by our belief are graffed in to Christ.
So when the time comes (at Christ's future return), Paul shows they will believe on Jesus once the stupor God put upon them is removed. This is why Zechariah 12 at the end shows there will be a great mourning for Christ by the orthodox Jews in that future time.
Once again, I will gladly read all you wright and try to adequately respond, but the basis of everything is in these points:
And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise. (Gal 3)
But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now...Now we, brethren, as Isaac was, are the children of promise. (Gal 4)
They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed. (Rom 9)
3. Is he a seed of Abraham, that is one born after the flesh, and not born after the spirit as Isaac was? Is he a child of promise and of Abraham counted for the seed of Abraham, that is a child of the flesh and believes not in Christ?
I.e. there is no seed of promise by the flesh.
For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children...But Jerusalem which is above is free, which is the mother of us all. So then, brethren, we are not children of the bondwoman, but of the free. (Gal 4)
Know ye therefore that they which are of faith, the same are the children of Abraham. (Gal 3)
4. Who are the children of Abraham by Hagar, and who are the children of Abraham by the freewoman, as Sarah?
I.e. the children of Abraham after the flesh, are the child of bondage by Hagar, and the children of Abraham after the Spirit by faith are children of the freewoman Sarah.