He calls them to the land after He returns. They are not holy now. As for the nation in a day thing the context is
This is incorrect. He has been calling them back to the land to purge out the unbelievers, Both Isaiah and Ezekiel directly address this. So they are called back as unbelievers.
EZ. 20:
33 As I live, saith the Lord God, surely with a mighty hand, and with a stretched out arm, and with fury poured out, will I rule over you:
34 And I will bring you out from the people, and will gather you out of the countries wherein ye are scattered, with a mighty hand, and with a stretched out arm, and with fury poured out.
35 And I will bring you into the wilderness of the people, and there will I plead with you face to face.
36 Like as I pleaded with your fathers in the wilderness of the land of Egypt, so will I plead with you, saith the Lord God.
37 And I will cause you to pass under the rod, and I will bring you into the bond of the covenant:
38 And I will purge out from among you the rebels, and them that transgress against me: I will bring them forth out of the country where they sojourn, and they shall not enter into the land of Israel: and ye shall know that I am the Lord.
He calls them to the land after He returns. They are not holy now. As for the nation in a day thing the context is
Isaiah 66:5
Hear the word of the Lord , ye that tremble at his word; Your brethren that hated you, that cast you out for my name's sake, said, Let the Lord be glorified: but he shall appear to your joy, and they shall be ashamed.
Isaiah 66:6
A voice of noise from the city, a voice from the temple, a voice of the Lord that rendereth recompence to his enemies.
He deals with His enemies at the end of the tribulation. Not in 1948
Isaiah 66:8
Who hath heard such a thing? who hath seen such things? Shall the earth be made to bring forth in one day? or shall a nation be born at once? for as soon as Zion travailed, she brought forth her children.
We should all know when that time of travail is. It certainly was not 1948
Isaiah 66:12
For thus saith the Lord , Behold, I will extend peace to her like a river, and the glory of the Gentiles like a flowing stream: then shall ye suck, ye shall be borne upon her sides, and be dandled upon her knees.
That is future...not past.
It is clear when Isa 66 is is about
Isaiah 66:15
For, behold, the Lord will come with fire, and with his chariots like a whirlwind, to render his anger with fury, and his rebuke with flames of fire.
NOT 1948.
Nearly all these verses refer to His physical return to earth. He goes to Petra to fight for them against the Antichrist. Marches them to Jerusalem, the nation mourns and cleanses the temple , Jesus sets up the judgment of the peoples, and then the millenial kingdom starts.
But make no mistake, May 14, 1948 began the fulfilment of the return of Israel to her land. To be judged and purged by god for the Second coming but it is prophecy.