While the saved reconnect with God, Satan and his followers are trapped on Earth by themselves. After a thousand years God will resurrect the lost for the final judgment before destroying sin and sinners.
The millennium is the thousand-year reign of Christ with His saints in heaven between the first and second resurrections. During this time the wicked dead will be judged; the earth will be utterly desolate, without living human inhabitants, but occupied by Satan and his angels. At its close, Christ with His saints and the Holy City will descend from heaven to earth. The unrighteous dead will then be resurrected, and with Satan and his angels will surround the city; but fire from God will consume them and cleanse the earth. The universe will thus be freed of sin and sinners forever. (Rev. 20; 1 Cor. 6:2, 3; Jer. 4:23-26; Rev. 21:1-5; Mal. 4:1; Eze. 28:18, 19.)