all Israel will be saved

Besides the numerous OT prophecies 
concerning the restoration of Israel as a people, 
there is Romans 11:26 that says: "all Israel will be saved."

I believe Charles Hodge, being honest with the text, 

came to the correct conclusion: 

"Israel here must mean the Jewish people, 

and 'all Israel' the whole nation. 

The Jews, as a people, are now rejected; 

as a people they are to be restored. 

As their rejection, although national, 

did not include the rejection of every individual, 

so their restoration though national,
need not include the salvation of every Jew. 

All Israel does not mean all the true people of God, 

as Augustin, Calvin, and others explain it; 

nor all the elect Jews -- i.e. all that part of the nation 

which constitute 'the remnant according to the election of grace' 

--but the whole nation, as a nation."

(Hodge's Commentary on Romans 11:26).

"For I do not desire, brethren, 

that you should be ignorant of this mystery, 

lest you should be wise in your own opinion, 

that blindness in part has happened to Israel 

until the fullness of the Gentiles has come in. 

And so all Israel will be saved, as it is written:
“The Deliverer will come out of Zion,
And He will turn away ungodliness from Jacob;
For this is My covenant with them,
When I take away their sins.”
Concerning the gospel, they are enemies for your sake, 

but concerning the election,

they are beloved for the sake of the fathers. 

For the gifts and the calling of God are irrevocable." 

Romans 11:24-29