The Great White Throne Judgment
Revelation 20:11-15
Then I saw a great white throne and Him who sat on it, from whose face the earth and the heavens fled away. And there was found no place for them. [Rev 20:11]
Like the seven seals of judgment that prepares for the Lords return [ref. Rev 19:11-16], there will be a final judgment [the Great White Throne Judgment] that prepares for a new heaven and a new earth [Rev 21:1].
It is important to distinguish the new heaven and new earth [i.e., the New Jerusalem] from the Millennium [Rev 20:1-10]. The New Jerusalem is the Eternal State. Citizens of this Eternal City will all be in resurrected bodies dwelling in the presence of God forever.
The Millennial Kingdom, however, will be a place where the Church, the Old Testament saints, and the Tribulation saints are in their resurrected bodies ruling and reigning with Christ. But there will be multitudes in the Millennium with mortal bodies [i.e., the 144,000 Jews in Rev 7:1-8; 14:1-5; a remnant of Jews sealed in the wilderness [Rev 12:6; Isa 16:3-4]; and Gentile believers who survive the Tribulation. These live into the Millennium and repopulate the earth, which will be re-established in glory like the time of Creation.
At the end of the Millennium, however, Satan will be loosed from the abyss and lead a final rebellion. He will deceive many who are born in the Millennium. But John records, fire came down from God out of heaven and devoured them. [Rev 20:9]
There then remains a final work before the New Jerusalem: Judgment of nonbelievers, i.e., the unfaithful dead. This comes at the Great White Throne judgment. It will be a judgment of the souls in Hades from unfaithful Cain to the unfaithful rebellious at the end of the Millennium [i.e., from Gen 4 through Rev 20, respectively]. It will be a final purge of sin that ushers in the Eternal State. Our citizenship will finally be fully in heaven. This is the place where Jesus said, I go and prepare a place for you.
The final chapters in Revelation are without a doubt the best! And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away. [Rev 21:4].
Be encouraged ye saints of the Lord; the best is yet to come!