There has to be a separation of Israel from the rest of the world, because God had His people as Israel and not the rest of the world, then He sent salvation to the rest of the world too.
But that Israel is not excluded, we are grafted into Israel, and although have a new name ( Christians) are of Israel too with the name blessed by God of Israel.
Genesis 32:28 And he said, Thy name shall be called no more Jacob, but Israel: for as a prince hast thou power with God and with men, and hast prevailed.
Isaiah 65:15 And ye shall leave your name for a curse unto my chosen: for the Lord God shall slay thee, and call his servants by another name:
Those Isaiah 65:15 people? they are the House of Judah in Jerusalem... The House of Israel of Solomon's divided kingdom didn't have a temple, the House of Judah did.(see Isaiah 65+66, below)
Not ALL of us ARE grafted-in, by Pauline theology. Ιησους'
other sheep already hear His voice and already believe on Him through the words of the 11 Disciples.
John 17:20 Neither pray I for these alone, but for them also which shall
believe on Me through their word;
John 15:26-27 when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, He shall testify of Me:[27] And ye also shall bear witness, because
ye have been with Me from the beginning.
John 10:16 And other sheep I have, which are not of this fold: them also I must bring, and they shall hear My voice: and there shall be
one fold, one shepherd.
Isaiah 65:1-10 I became manifest to them that asked not for Me; I was found of them that sought Me not: I said, Behold, I am here, to a nation, who called not on My name.
[2] I have stretched forth My hands all day to a disobedient and gainsaying people, to them that walked in a way that was not good, but after their sins.[3]
This is the people that provokes Me continually in My presence; they offer sacrifices in gardens, and burn incense on bricks to devils, which exist not.[4] They lie down to sleep in the tombs and in the caves for the sake of dreams, even they that eat swine’s flesh, and the broth of their sacrifices: all their vessels are defiled:[5] who say, Depart from me, draw not nigh to me, for I am pure. This is the smoke of my wrath, a fire burns with it continually.[6] Behold, it is written before Me: I will not be silent until I have recompensed into their bosom,[7] their sins and the sins of their fathers, saith the Lord, who have burnt incense on the mountains, and reproached Me on the hills: I will recompense their works into their bosom.
[8] Thus saith the Lord, As a grape-stone shall be found in the cluster, and they shall say, Destroy it not; for a blessing is in it: so will I do for the sake of him that serves me, for his sake I will not destroy them all.[9] And I will lead forth the seed that came of Jacob and of Juda, and they shall inherit my holy mountain: and mine elect and my servants shall inherit it, and shall dwell there. [10] And there shall be in the forest folds of flocks, and the valley of Achor shall be for a resting-place of herds for My people, who have sought Me.LXX
Isaiah 66:1-3 Thus saith the Lord, Heaven is My throne, and the earth is My footstool: what kind of a house will ye build Me? and of what kind is to be the place of My rest?[2] For all these things are Mine, saith the Lord: and to whom will I have respect, but to the humble and meek, and the man that trembles at My words?[3] But
the transgressor that sacrifices a calf to Me, is as he that kills a dog; and he that offers fine flour, as one that offers swine’s blood; he that gives frankincense for a memorial, is as a blasphemer. Yet
they have chosen their own ways, and their soul has delighted in their abominations.LXX
The divided kingdom of Solomon is still divided, and will be until the day of Jezreel.