Hate to start an arguement here, because it happens I am a lover of Israel, as an elder brother, BUT Israel is not a Christian people, barely Jewish in this era and were declared a nation by reason of their borders alone. The Church is the new Israel to which you clearly see through out the New Testament. To the Church are the promises for Israel as the promise of the New Jerusalim.
The purpose of the Old Testament is to reveal to God’s Chosen People the land of milk and honey (Heaven), coming High Priest, Christ (the new Adam), the coming Church, the kingdom of priests, the family of God, the pruning of the old dead branch of the fig tree, the newly grafted branch, (Gentile believers) the Sacrament of Baptism over circumcision, etc., etc. The Church is become the spiritual children of Abraham.
I think Romans 11: 25-27 addresses your concern on Israel
25For 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.
26And 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:
27For this is my covenant unto them, when I shall take away their sins.