That is a TEMPORARY situation as clearly explained by Paul.
Rom 11:1-7 I say then, Hath God cast away his people? God forbid. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin. (2) God hath not cast away his people which he foreknew. Wot ye not what the scripture saith of Elias? how he maketh intercession to God against Israel, saying, (3) Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life. (4) But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal. (5) Even so then at this present time also there is a remnant according to the election of grace. (6) And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then is it no more grace: otherwise work is no more work. (7) What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded
So Paul tells us that they are not cast away. But their blindness is temporary and the they will be restored.
Rom 11:11-15 I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy. (12) Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles; how much more their fulness? (13) For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify mine office: (14) If by any means I may provoke to emulation them which are my flesh, and might save some of them. (15) For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead?
So here Paul show that the "casting away of them" is temporary.