Israel is a light to the unconverted Jews and Gentiles; the Israel of God consists of all those Jews and Gentiles who have been inwardly circumcised (Gal 6:16). We are Israel in Christ, and all nations, Jews and Gentiles are being progressively incorporated into God's Israel.
Israel after the flesh consists of all Jews, converted and unconverted (I Cor 10:18).
Most of Israel after the flesh is not in the Israel of God, i.e. does not belong to God, but in his covenant mercy He did not wipe out the Jewish nation in A.D.70, He has always kept a true remnant of believers within them, in the New Testament dispensation He has expanded Israel/the Church to include Gentiles in equality with Jews, and He has promised to bring the unconverted of Israel after the flesh back into the Israel of God, which will correspond with great Gospel blessing to the world (ROM 9-11).
This is "Expansion Theology" (Isaiah 54) ; the Lord Jesus Christ will expand His Israel by His Gospel in history, until the Earth is full of the knowledge of God as the waters cover the sea.
As concerning the Gospel the unconverted Jews are enemies for your sakes, but as touching the election, the unconverted Jews are beloved for the fathers' sakes (Rom 11:28).