Romans 11:25-29

25 For I do not want you, brethren, to be uninformed of this mystery, lest you be wise in your own estimation, that a partial hardening has happened to Israel until the fulness of the Gentiles has come in;

26 and thus all Israel will be saved; just as it is written, "The Deliverer will come from Zion, He will remove ungodliness from Jacob."

27 "And this is My covenant with them, When I take away their sins."

28 From the standpoint of the gospel they are enemies for your sake, but from the standpoint of God's choice they are beloved for the sake of the fathers;

29 for the gifts and the calling of God are irrevocable.

This passage reaffirms God's promise to the nation of Israel, and to the Jews nationally. The Jewish nation has not and will not be rejected. But we know that not every Jew will be saved, because Judas Iscariot is a Jew and was not saved.

Paul's earlier statement in Romans 2:28-29 helps to understand how God views His people, the Jews:

28 For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh.

29 But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God.

So just as you might have a Christian home, yet some member of the family might reject God and Christ, so also among the Jews there will be some who have rejected God and never embraced the truth.