But it is not as though the word of God has failed: for they are not all Israel, who are of Israel; neither, because they are Abraham's seed, are they all children; but, "In Isaac shall your seed be called." That is, the children of the flesh are not the children of God; but the children of the promise are reckoned for a seed.

Romans 11:2-7

God did not cast off His people whom He foreknew. Or know ye not what the Scripture says of Elijah? how he pleads with God against Israel: "Lord, they have killed Thy prophets, they have digged down Thy altars; and I am left alone, and they are seeking my soul." But what says the answer of God to him? "I left for Myself seven thousand men, who have not bowed the knee to Baal." read more.
Even so, then, at this present time also, a remnant, according to an election of grace, has been reserved. But, if by grace, it is no longer of works; otherwise the grace becomes no longer grace. [But, if of works, it is no longer grace; otherwise, the work is no longer work.] What, then? What Israel is seeking for, this he did not obtain; but the election obtained it, and the rest were hardened;