One of the core doctrines in Christianity is that Jesus Christ will return one day. Known as The Second Coming, the Bible teaches that Christ will come back to the earth at an unknown time to destroy the enemies of God, rid the world of sin, reward followers, and establish peace. However, because Christians interpret key passages differently, there is not uniform agreement as to what events, if any, lead up to this event.
The three views on the end times that have been dominant in the history of Christianity are postmillennialism, amillennialism, and premillennialism. As their names suggest, the differences center on their understanding of the 1,000-year “millennial period,” which is mentioned in Revelation 20:1-6,
"And I saw an angel coming down out of heaven, having the key to the Abyss and holding in his hand a great chain. 2 He seized the dragon, that ancient serpent, who is the devil, or Satan, and bound him for a thousand years. 3 He threw him into the Abyss, and locked and sealed it over him, to keep him from deceiving the nations anymore until the thousand years were ended. After that, he must be set free for a short time. 4 I saw thrones on which were seated those who had been given authority to judge. And I saw the souls of those who had been beheaded because of their testimony for Jesus and because of the word of God. They had not worshiped the beast or his image and had not received his mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years. 5 (The rest of the dead did not come to life until the thousand years were ended.) This is the first resurrection. 6 Blessed and holy are those who have part in the first resurrection. The second death has no power over them, but they will be priests of God and of Christ and will reign with him for a thousand years" (NIV, emphases mine)
The theological term millennium is derived from the Latin word "mille," meaning one-thousand. Whether the millennial period as described in Revelation is literal or figurative is at the core of interpretative disagreements. Other significant points of disagreement between the views are what events, if any, the Bible teaches will precede the millennium, what activities will occur within the period, and if Jew and Gentile are distinguished at the time.