Here are the passages on Israel's promised restoration, OT and NT. The rebuttals of this are that 1) Israel has been cast off forever, and 2) that Israel actually means *many Christian nations.* Both of these arguments are absurd on their face, despite the fact for many centuries the Christian Church began to deny the Hope of Israel. Israel does mean Israel, the nation--not many Christian nations. And the NT confirmation of Israel's Hope declares, explicitly, that Israel has not fallen forever.
Paul's argument in Rom 9-11 is extremely compelling. The only concern those opposed to Israel's noted restoration there is the fact in chs. 9 and 10 Paul explains that Israel in the current age has been reduced to less than a nation--to a mere remnant. But this in no way invalidates Paul's conclusion in ch. 11 that Israel will be completely restored to national status and to status as God's People.
The Hope of Israel began with God's promise to Abraham to have biological descendants form into a nation inheriting the land of Canaan, an explicit description of a single nation. Later, God promised Abraham many more nations of faith without taking back His original promise of Israel, Abraham's national posterity.
Gen 12. 2 I will make you into a great nation.
Isa 49.8 This is what the Lord says:
“At just the right time, I will respond to you.
On the day of salvation I will help you.
I will protect you and give you to the people
as my covenant with them.
Through you I will reestablish the land of Israel
and assign it to its own people again.
9 I will say to the prisoners, ‘Come out in freedom,’
and to those in darkness, ‘Come into the light.’
They will be my sheep, grazing in green pastures
and on hills that were previously bare.
10 They will neither hunger nor thirst.
The searing sun will not reach them anymore.
For the Lord in his mercy will lead them;
he will lead them beside cool waters.
11 And I will make my mountains into level paths for them.
The highways will be raised above the valleys.
12 See, my people will return from far away,
from lands to the north and west,
and from as far south as Egypt.”
13 Sing for joy, O heavens!
Rejoice, O earth!
Burst into song, O mountains!
For the Lord has comforted his people
and will have compassion on them in their suffering.
14 Yet Jerusalem says, “The Lord has deserted us;
the Lord has forgotten us.”
15 “Never! Can a mother forget her nursing child?
Can she feel no love for the child she has borne?
But even if that were possible,
I would not forget you!
16 See, I have written your name on the palms of my hands.
Always in my mind is a picture of Jerusalem’s walls in ruins.
Luke 2.32 "a light for revelation to the Gentiles, and the glory of your people Israel.”
Matt 3.2 and saying, “Repent, for the kingdom of heaven has come near.”
Luke 21.24 Jerusalem will be trampled on by the Gentiles until the times of the Gentiles are fulfilled.
Acts 1.6 Then they gathered around him and asked him, “Lord, are you at this time going to restore the kingdom to Israel?”
Rom 11.I ask then: Did God reject his people? By no means!... 11 Again I ask: Did they stumble so as to fall beyond recovery? Not at all!... 15 For if their rejection brought reconciliation to the world, what will their acceptance be but life from the dead?... 23 And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again. 24 After all, if you were cut out of an olive tree that is wild by nature, and contrary to nature were grafted into a cultivated olive tree, how much more readily will these, the natural branches, be grafted into their own olive tree!... 25 I do not want you to be ignorant of this mystery, brothers and sisters, so that you may not be conceited: Israel has experienced a hardening in part until the full number of the Gentiles has come in, 26 and in this way all Israel will be saved. As it is written:
“The deliverer will come from Zion;
he will turn godlessness away from Jacob.
27 And this is my covenant with them
when I take away their sins.”
28 As far as the gospel is concerned, they are enemies for your sake; but as far as election is concerned, they are loved on account of the patriarchs, 29 for God’s gifts and his call are irrevocable.