What does Revelation 20:12 mean?
Standing before the great white throne are the resurrected dead who were not saved—those who did not accept Christ during life (John 3:36). These doomed individuals represent all classes of human beings, from paupers to princes. They are being judged by the Faithful and True Judge, who died to provide a way of escape from sin and eternal punishment (John 3:16–18). Those assembled at the great white throne rejected Jesus' redemptive work and His gracious invitation to believe on Him and have everlasting life (John 6:37). As a result, rather than being judged on the basis of Christ's work, they face the record of their sins when the books are opened. The record shows they sinned and failed to repent.At the same time, another book is opened, which is the book of life. As verse 15 points out, the doomed are sentenced to eternal punishment because their names are not written in the book of life. Being judged "by what was written in the books, according to what they had done" may imply there are degrees of punishment in hell, but the absence of a defendant's name from the Lamb's book of life is the determining factor in his or her consignment to hell.
Revelation 20:11–15 occurs just after the end of the kingdom reign of Christ on earth, when Satan was released for a brief time. He gathered rebel forces together to battle God and His saints, but lost and was cast into the lake of fire (Revelation 20:7–10). The next event described by John is the judgment at the great white throne. This is the point where unbelievers are judged according to their actions—a death sentence for everyone not saved through Christ (Romans 6:23). Chapter 21 describes the descent of the New Jerusalem from heaven and the beginning of the eternal age.
Revelation chapter 20 represents the final lesson, final judgment, and final victory of the end times. Satan is bound, but not destroyed, and released after a thousand years of peace and righteousness. Proving that no evidence or reason to believe in and follow Jesus is enough for those determined to rebel, some follow Satan and are destroyed in a rebellion. Those who died without faith in Christ, through all of history, are resurrected to face the great white throne judgment. There, they are sentenced for sin and consigned eternally to the lake of fire.