Millenarianism, generally speaking, is belief in a future positive transformation of society. Christian millenarianism, also known as millennialism, is the belief that there will be a 1,000-year period in the future in which Christ will literally rule on earth. The word millenarianism comes from the Latin word for “1,000”—millennium. Millennialism is also sometimes called chiliasm, which is from the Greek word for “1,000.” Those who hold this belief are called millennialists or millenarians (not to be confused with Millennials, who are the generation of people born between the years 1980 and 2000).
A belief in millenarianism is primarily supported by 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. He seized the dragon, that ancient serpent, who is the devil, or Satan, and bound him for a thousand years. 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. 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 about Jesus and because of the word of God. They had not worshiped the beast or its image and had not received its mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years. (The rest of the dead did not come to life until the thousand years were ended.) This is the first resurrection. Blessed and holy are those who share 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.”
If these verses are to be understood literally, then at some point in the future, before the eternal state in the new heavens and new earth, Jesus will rule as a literal, visible king on this earth. This will be a time of peace and prosperity as all the governments and systems of the world operate in harmony with the laws of God, and Satan is unable to influence people negatively. All people on earth at the time of the millennium will at least give lip service to Jesus’ lordship. However, when Satan is released after the 1,000 years is up, rebellion breaks out immediately (Revelation 20:7–10).
After this final rebellion, everything is brought to consummation. Final judgment is rendered, and those who belong to the Lord will enter the new heavens and new earth. There will be no further chance of sin or rebellion.
Premillennialists believe that Christ will come back before this 1,000-year period to establish what is often called the “millennial kingdom.” Postmillennialists believe that the 1,000-year reign will be ushered in by the preaching of the gospel as nations and institutions are reformed along biblical guidelines and as the world becomes predominantly Christian. This worldwide acceptance of the gospel will usher in a spiritual reign of Christ through the Church, and He will return when the 1,000 years is up. According to postmillennialism, the 1,000 years mentioned in Revelation 20 may or may not be a literal number of years. Amillennialists believe that there will be no literal 1,000-year kingdom. Amillennialists generally believe that the number 1,000 is symbolic for perfection or fulfillment and that Revelation 20 speaks of the current age in which we live as Christ reigns in the Church and in the hearts of His people. According to amillenialism, Satan is currently “bound” in that he cannot hinder the preaching of the gospel as Christ builds His Church. All three of these views are considered to be orthodox/evangelical options.
When people speak of millenarians or millennialists, they are usually thinking of premillennialists—those who are looking for Christ to return before the kingdom is established on earth and who, generally speaking, expect things on this earth to get increasingly worse as opposition to the gospel and persecution increase.
Some cults have adopted a millenarian mindset and taken extreme measures to ensure survival until Christ (or whomever they’re expecting) returns. These cults usually view themselves as the last remaining outpost of “true religion” in an increasingly hostile world. Some people try to use the beliefs of millennialist cults to argue against millennialism in general; however, the fact that a cult adopts a certain belief says nothing about the validity of that belief. Millennialism, the belief that Jesus Christ will judge the world and establish a 1,000-year kingdom on earth, has clear biblical support.