Millennialism comes from the millennium, the Latin for "a thousand years." The Greek equivalent is chiliasm. It is a belief advanced by some religious denominations that a golden age or paradise will occur on the Earth prior to the final judgment of God and future the eternal state of the world that is to come.
Both Christianity and Judaism have produced messianic movements which featured millennialist teachings—such as the notion that an earthly kingdom of God was at hand. These movements often led to social unrest.
Similarities to Christian millennialism appear in other religions, such as Zoroastrianism, which identified successive thousand-year periods, each of which will end in a cataclysm of heresy and destruction, until the final destruction of evil and of the spirit of evil by a triumphant king of peace at the end of the final millennial age.
Scholars have also linked various other social and political movements, both religious and secular, to millennialist metaphors.
Christian millennialist thinking is based upon the book of Revelation. The specific verses are found in Revelation 20. The verses describe the vision of an angel who descended from heaven with a large chain and a key to a bottomless pit, and captured Satan, imprisoning him for a thousand years:
He seized the dragon, that ancient serpent, who is the Devil and Satan, and bound him for a thousand years and threw him into the pit and locked and sealed it over him, so that he would deceive the nations no more, until the thousand years were ended. After that, he must be let out for a little while.
Revelation 20: 2-3
The Book of Revelation then describes a series of judges who are seated on thrones, as well as John's vision of the souls of those who were beheaded for their testimony in favor of Jesus and their rejection of the mark of the beast. These souls:
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. Over these the second death has no power, but they will be priests of God and of Christ, and they will reign with him a thousand years
Revelation 20: 4-6
The are four basic views regarding the millennium in Christianity. The following video clip describes these views in more detail.