When Jesus Christ returns to reign for 1000 years, then those men and women who are to make up His government, will either accompany Him or be on earth, ready for Him. They must have been prepared, prior to His return, for the offices to which they have been assigned.
I would consider that only in the gathered Israelites of God, every born again Christian; Jew and Gentile, would conditions be suitable for the selection and training of those people.
Jeremiah chapter 29 The words of the Lord to the exiles of Judah and Israel.
Jeremiah 29:13-14 When you seek Me, if you search wholeheartedly you will find Me. I shall restore your fortunes and gather you from all the places to which I have banished you. I shall settle you in the Land from which you went into exile.
At this time, the Lord has to be searched for in faith. Those righteous Israelites who do seek and find the Lord, will be gathered and settled into all of the Promised Land. Those Israelites who revolt and rebel will not set foot on the soil of Israel. Ezekiel 20:37-38
Matthew 25:31 When the Son of Man comes in His glory, His angels with Him, He will sit on His Throne.
Matthew 25:32 With all the nations gathered before Him. He will separate them into two groups, as the sheep from the goats.
Matthew 25:33 The sheep on the right and the goats on the left.
Matthew 25:34 Then the King will say to those on the right; Come, take possession of the Kingdom.
Those righteous and wicked nations existing on the earth at the beginning of the
Millennium will be judged. Then, all of ”His chosen people” will join Israel in the Land. Matthew 24:31 The Land cannot be empty at the time of His Return as the two Witnesses are there in Jerusalem, then when they ascend to Heaven an earthquake will kill 7000 people. Revelation 11:13
Before that, is the gathering and judgement of the 12 tribes of Israel, as prophesied in Ezekiel 37:21-22, Amos 3:9 and Ezekiel 20:35-36 is another event in the “wilderness of the Peoples” where the Lord separates the Israelites and allows the righteous; all faithful Christians, to settle in the Land.
Revelation chapter 7 … the 144,000 sealed for protection
Before the Day of the Lord- otherwise, why need protection? Then, after the great and terrible Day of the Lord:
…. I saw a vast throng before the Throne, beyond counting.
…..They are those who have passed the Great ordeal.
….. The Lord will be their shepherd and God will wipe every tear from their eyes.