Has God formally rejected Israel? No. First, a remnant was owned at Pentecost. Second, the reception of the Gentiles was to provoke the Jews to jealousy. Third, the Redeemer will yet come to Zion, and so Israel shall be saved as a nation.
Elijah's failure is the only failure of the prophets recorded in the New Testament, because he spoke to God against His people. God's reply was, "I have reserved to myself seven thousand men who have not bowed the knee to the image of Baal."
The remnant today is a remnant of grace and not of works. They are in the Church. The elected ones have received the promise given to Abraham.
After the flood, men sought to make themselves a name in order that they might not be scattered, but they were scattered by God in judgment at Babel and formed into nations. The result was idolatry.
The God of glory called Abraham to begin a new family on the earth. Up to this time there had been no head of a race except Adam, the father of sinners. The promises to Abraham were through election and on the basis of grace. Abraham became the seed of God on the earth.
Some have spoken of this as the moral birth of mankind; had it not been for this, man's race would have perished. In Abraham, the seed of God, were election, promise and calling.
Israel as a whole is in slumber; their eyes have been darkened; did they stumble that they should fall? No! but rather that salvation might come to the Gentiles to provoke Israel to jealousy. For them to be cast away, brought blessing to the Gentiles, but the receiving them again is like resurrection from the dead.
Abraham is the rootstock of the promises and of faith; the rootstock is holy, so are the branches. "Holy"
here means to be set apart for a special purpose. When some branches were broken off of the olive tree, wild branches, Gentiles, were grafted in. Do not boast, Gentiles, the root bears thee. They were broken off because of unbelief; thou standest by faith.
The Gentiles should be careful that they receive not the same breaking off of the branches as was done to Israel; severity upon Israel, goodness to the Gentiles if they continue in His goodness, otherwise they shall be cut off.
When Israel by faith return to their place, they shall be grafted into their own olive tree again. Is it not proper that if they repent, the natural branches should be grafted in again to the good olive tree?
The fullness of the Gentiles will bring the return of all Israel; then blindness in part will be over. The Deliverer (Christ) from Zion shall restore Jacob. Because of election, "they are beloved for the fathers' sakes. For the gifts and calling of God are without repentance."
In time past we had not believed, but mercy was shown us. Israel also has not believed in the past, so they also shall find mercy; God had found all in unbelief that mercy might be shown to all.
The failure of the Jewish system allowed the Gentiles to come into the good olive tree, and the failure of the Gentile system will let Israel back in.