Two thirds of the called out have been taught a merger of Judaism and Christianity..which are actually two opposing theologies. Because they have departed from the truth and, in the spirit of Esau, have given their own birthright to a carnal group of non-believers,they have become the new "lost sheep of Israel"

For Christ had remade Israel..
And the vessel that he made of clay was marred in the hand of the potter: so he made it again another vessel, as seemed good to the potter to make it. Jer. 18.4

The Mosaic covenant was annulled because of Israel's continued apostasy. The Abrahamic covenant, however, could not be broken for God had made it with himself (Abraham was sleeping). It is the covenant of Abraham that forms a basis for the church of Jesus Christ. From Abraham through David to Jesus to His followers..the born again are the seed of Abraham.

It's circumcision of the heart..all Israel shall indeed be saved..you just need to know who the real Israel is.