"The force of 'all Israel' in Rom 11 is from the preceding section; those who have faith are in the tree. The tree is the Israel of God, Jew or Gentile. All that is justified from their sins and inherits the NHNE. For both of those reasons (who, and unto what) it is not about the restoration of Israel or Judaism in Israel. Paul provocatively tried to get his own people into the mission and did not want the Gentiles to be proud either, just because so few Jews were in."
"That the fullness of the Gentiles,” etc. The meaning then is, — That God had in a manner so blinded Israel, that while they refused the light of the gospel, it might be transferred to the Gentiles, and that these might occupy, as it were, the vacated possession. And so this blindness served the providence of God in furthering the salvation of the Gentiles, which he had designed. And the fullness of the Gentiles is to be taken for a great number: for it was not to be, as before, when a few proselytes connected themselves with the Jews; but such was to be the change, that the Gentiles would form almost the entire body of the Church."
"26. And so all Israel, etc. Many understand this of the Jewish people, as though Paul had said, that religion would again be restored among them as before: but I extend the word Israel to all the people of God, according to this meaning, — “When the Gentiles shall come in, the Jews also shall return from their defection to the obedience of faith; and thus shall be completed the salvation of the whole Israel of God, which must be gathered from both; and yet in such a way that the Jews shall obtain the first place, being as it were the first-born in God’s family.” This interpretation seems to me the most suitable, because Paul intended here to set forth the completion of the kingdom of Christ, which is by no means to be confined to the Jews, but is to include the whole world. The same manner of speaking we find in Ga 6:16. The Israel of God is what he calls the Church, gathered alike from Jews and Gentiles; and he sets the people, thus collected from their dispersion, in opposition to the carnal children of Abraham, who had departed from his faith." From:
http://www.sacred-texts.com/chr/calvin/cc38/cc38014.htm John Calvin's commentaries
In general, the Reformation Christians followed this interpretation of Romans 11: 25-26. This does not mean at all that Reformation Christian doctrine followed what is called Five Point Calvinism. This includes the doctrines of Total Depravity, Unconditional Election, Limited Atonement, Irresistible Grace, and Preservation of the Elect.
I have studied the influence of Theodore Beza, successor to Calvin, on the Calvinist and Protestant doctrine of the ekklesia or church. John Wyclife, of England, translated the first Bible into English in 1382, not from the original languages, but from the Latin. Wyclife translated the Latin word ecclesiam into chirche (in old English spelling):
But then William Tyndale in his 1526 New Testament translated ekklesia as congregation, except for Acts 14: 13 and Acts 19: 37 where he used churche, meaning a pagan place of worship. Tyndale broke with Catholic tradition and used congregation for ekklesia something which might have contributed to his being strangled at the stake by the Catholics.
And after the death of John Calvin, Theodore Beza in 1556 returned to the use of church to translate ekklesia - and the Geneva Bible followed him, using church instead of congregation. Beza returned to the Catholic Capital C Church translation of ekklesia as chirche.
William Tyndale, who was a one man translator of the Greek Textus Receptus into the English of his time - 1525-1536 or so - would not have agreeed at all with Beza's return to the use of the Roman Catholic chirche as a translation of ekklesia. Tyndale as a kind of one person Remnant of God would have insisted that the meaning of the Greek word ekklesia at the time the New Testament was written must be preserved in the English translation of that word. Ekklesia has a meaning closer to meeting, assembly or congregation than to the several meanings of chirche in 1525.
The old English word circe, chirche, kirk or churche is said to have meant the house of a lord, a place of pagan worship, or circe, the Greek goddess. But circe, or churche was redefined by the clergy. Neither churche as a house of a pagan lord or circe as the Greek goddess have the same meaning as the Greek word ekklesia.
What Beza did, in effect, in returning to chirche as a translation of ekklesia, was to move back toward a definition of the church as an institution of man with a clergy class who claim to have control over the beliefs of the congregation, as in Roman Catholicism.
I Peter 5: 2-3 says "Feed the flock of God which is among you, taking the oversight thereof, not by constraint, but willingly; not for filthy lucre, but of a ready mind;
3. Neither as being lords over God's heritage, but being ensamples to the flock."
And so the Capital C Church - as a proper rather than a common noun - became pretty much equal to the Body of Christ. And then starting in the 19th century the dispensationalists take the idea of the Capital, C Church and place it beside Old Covenant Physical Israel and claim as one of their starting postulates that God now has two peoples, Israel and the Church.
By Israel they mean Israel as those of the physical bloodline, which in texts of the New Testament is done away with, and put Israel alongside the Capital C Church, which has been given a meaning different from the original Greek ekklesia. I know about Paul's use of ekklesia appearing to be the Body of Christ in Colossians 1: 18 and 1: 24.
"And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence." Colossians 1: 18
"Who now rejoice in my sufferings for you, and fill up that which is behind of the afflictions of Christ in my flesh for his body's sake, which is the church:" Colossians 1: 24
In Colossians 4: 15-16 Paul uses ekklesia to refer to a local congregation. And in Philemon 1: 2, which is a short letter considered to be written at the time of Paul's imprisonment in Rome in about 58 to 62 A.D., Paul used ekklesia to refer to a local church. Philemon 1: 2 says "And to our belived Apphia and Archippus our fellowsoldier, and to the church in thy house."
If Paul in Colossians 1: 18 and 1: 24 intended to change the use of ekklesia from being a local congregation of Christians to being equal to the Body of Christ, the elect of God, he would likely have been consistent in its use in Colossians, Philemon and also in Ephesians.
When all or almost all members of a congregation are saved and of the elect, then a local ekklesia would be part of the Body of Christ. But what is taught in Matthew 13: 38-42 on the Parable of the Wheat and the Tares has to be included in a doctrine of the ekklesia, especially in a time of apostasy in the ekklesia where many church members are Tares,
