16 The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?
17 For** we being many are one bread, and one body:** for we are all partakers of that one bread.
18 Behold Israel after the flesh: are not they which eat of the sacrifices partakers of the altar?
If there is an Israel after the flesh it follows that there is an Israel after the Spirit
15 For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.
16 And** as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God.**
It looks to me like the Israel of God is “in Christ”.
11 Wherefore remember, that ye being in time past** Gentiles in the flesh,** who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
Those of us who were “Gentiles in the flesh” were aliens but now we heve been brought near, included in the commonwealth and the promises. The reconciliation is to Christ, and through Him into the olive tree, which is the Israel of God. Those wild branches who are grafted in are one with the natural branches. One bread. One body.
18 For through him we both have access by one Spirit unto the Father.19 Now therefore **ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;**Eph
This again speaks of grafting in, in a sense. “Gentiles in the flesh” are now in “Israel in the spirit” through reconciliation into the one new man. In Zechariah Israel is the Lampstand. The plan of God in Israel continues in the “ecclesia”, which is not Israel grafted into the Gentile believers, but is the “Gentiles in the flesh” grafted into the olive tree, to form a new creation, that is an extension of the original purpose of Israel, through Messiah Yashuah, a Jew of the lineage of David, the Root.
Christ first, the Root, then the remnant, the olive tree, the stump from which the new creature is formed by grafting in wild branches, becoming the ecclesia, which is the assembly detailed in Hebrews 12.
In my opinion this is the Israel of God.
Heb 12:22
But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to myriads of angels, 23 to the general assembly and church of the firstborn who are enrolled in heaven, and to God, the Judge of all, and to the spirits of the righteous made perfect, 24 and to Jesus, the mediator of a new covenant, and to the sprinkled blood, which speaks better than the blood of Abel.
All Israel will be saved because the cut-off branches will be grafted back into the new creation, the Israel of God, the olive tree.
Or something like that .02