But it is not as if the word of God [i.e., His promise to Israel] has failed [in its fulfillment]. For not all those descended from the Israelites are [truly] Israelites [i.e., God's people].

And Isaiah declares about [the nation of] Israel [Isa. 10:22-23], "[Even] if the number of Israelites were [as many] as the grains of sand in the ocean, [still only] a small minority will be saved.

God did not reject His people whom He knew previously. Or, do you not know what the Scriptures say in the passage where Elijah pleads with God against Israel?

And so [i.e., in this way] all the Israelites will be saved. [Note: The "all" here is thought by many to refer to a large number of the physical Jews who will be saved, not necessarily to every single individual Jew]. Even as it is written [Isa. 59:20-21], "The Deliverer [i.e., Christ] will come from Zion [i.e., the city of Jerusalem, or from the nation of Israel]. He will take away the wickedness from Jacob [i.e., the Jews]."