In this chapter we learn several important things about Israel: God did not reject His people; at the present time there is a remnant of Israel chosen by grace; some of Israel is hardened to not see the Gospel; they are not beyond recovery; because of their transgression, salvation has come to Gentiles; all Israel will be saved.
To read that God has hardened the hearts of some of Israel is difficult to grasp. Paul refers to it as a mystery. God has temporarily hardened Israel in part until all Gentiles who will believe the Gospel have come into the church. Then all Israel will be saved. He has hardened some to make room for us Gentiles! How truly glorious it will be when all Israel is saved. Paul calls it life from the dead. The thought of it causes him to emphatically declare, “Oh, the depth of the riches of the wisdom and knowledge of God! How unsearchable his judgments, and his paths beyond tracing out! …For from him and through him and to him are all things. To him be the glory forever! Amen” (11:33, 36). Let’s praise the One who is faithful to all His promises.