You had written:
“The 'great tribulation' is confined to Israel only because it is His vengeance against the land and the people of Israel.”
After you cited Luke 21
Luke 21: 22 For these be the days of vengeance, that all things which are written may be fulfilled.
23 But woe unto them that are with child, and to them that give suck, in those days! for there shall be great distress in the land, and wrath upon this people.
Yet, the very next line shows that lines 22 & 23 spoke of something long before the end times:
Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.
Lines 22 & 23 were prophesying, not about 2,000 years later, but about 37 years later.
It happened then, within the same generation, that the Romans came, destroyed the temple & the city, like Babylon had done may years earlier.
And the Jews were scattered amongst the Gentiles, suffering great persecutions & genocides, leading up to & including the worst of them, the Holocaust.
Then, after nearly 1900 years, the Gentiles began letting them go, and they began returning unto the land of Israel.
Large portions of Jerusalem, and in particular, the temple mount, are still trodden down of the Gentiles unto this very day.
The great tribulation will bring vengeance upon the nations of the Gentiles, but mercy to the land of Israel & to his people Israel:
Deuteronomy 32:43 Rejoice, O ye nations, with his people: for he will avenge the blood of his servants, and will render vengeance to his adversaries, and will be merciful unto his land, and to his people.
Isaiah 34:1 Come near, ye nations, to hear; and hearken, ye people: let the earth hear, and all that is therein; the world, and all things that come forth of it.
2 For the indignation of the LORD is upon all nations, and his fury upon all their armies: he hath utterly destroyed them, he hath delivered them to the slaughter.
8 For it is the day of the LORD'S vengeance, and the year of recompences for the controversy of Zion.
Ezekiel 25: 14 And I will lay my vengeance upon Edom by the hand of my people Israel: and they shall do in Edom according to mine anger and according to my fury; and they shall know my vengeance, saith the Lord GOD.
15 ¶ Thus saith the Lord GOD; Because the Philistines have dealt by revenge, and have taken vengeance with a despiteful heart, to destroy it for the old hatred;
16 Therefore thus saith the Lord GOD; Behold, I will stretch out mine hand upon the Philistines, and I will cut off the Cherethims, and destroy the remnant of the sea coast.
17 And I will execute great vengeance upon them with furious rebukes; and they shall know that I am the LORD,