Different Christians believe in different theories of the Judgment Day. Here are some of the theories that you can find out there.
1. Many Christians think the Bible teaches us about three judgment days:
(i) Judgment Seat of Christ: It is reserved for the judgment of Christians only. Born again believers in Christ Jesus will give an account of their lives to Christ. It will occur immediately following the rapture and it is about receiving rewards rather than being punished for the sins. The rapture includes the glorification or resurrection of the bodies of believers.
One of the passages pointed by those who believe in the three judgments include 2 Corinthians 5:10 "For we must all appear before the judgment seat of Christ, so that each of us may receive what is due us for the things done while in the body, whether good or bad" (NIV).
(ii) Sheeps and Goats Judgment: This judgment will take place at the end of Tribulation period that is after rapture occurs. Jesus will come and take all believers into heaven at the rapture. Those who remain and survive the tribulation and believe in Christ will gain opportunity to enter the Millennium of the Messiah.
(iii) Great White Throne Judgment: This is a final condemnation of the unrighteous dead at the end of all time, after the end of the world and before the beginning of the New Heavens and New Earth. This judgment is based on passages such as Revelation 20:12: "And I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books."
2. Other Christians believe there will be two judgments.
They claim Sheeps and Goats Judgment is the first judgment and will occur after the Tribulation period and before the Millennium of the Messiah. The second one is the "final judgment" and it is described in the Bible by passages about the Judgment Seat of Christ and Great White Throne Judgment - those speak of the same one. The final judgment will take place before the beginning of the New Heavens and New Earth.
3. Others claim The Judgment Day will happen one time.
Other Christians believe that all three of these judgments previously pointed speak of the same final judgment in Revelation 20:11-15. This will be the time that believers and unbelievers alike are judged.
4. For some Christians, including those who believe in "Full Preterism," the judgment day was already fulfilled in the 1st century.
They believe that all or a majority of Bible prophecy was fulfilled, with some pointing that it happened by AD 70 when Jesus came in the clouds, in the Great White Throne Judgment, when Jerusalem and the Temple were destroyed.
5. Others, including some "historicists" and "idealists," associate the judgment day to some historical events or personal experiences, taking the judgment with a non-literal approach.
Some Christians believe that the book of Revelation portrays the span of church history, from the 1st century to the return of Christ. Therefore, events in Revelation are symbolically interpreted to portray literal events in the life of the Church and that Kingdom of Heaven, and judgment may take place subjectively for the individual.