Millenarianism (also millenarism), from Latin "containing a thousand", is the belief by a religious, social, or political group or movement in a coming major transformation of society, after which all things will be changed. Millenarianism is a concept or theme that exists in many cultures and religions.
Millennialism is a specific type of Christian millenarianism, and is sometimes referred to as "chiliasm" from the New Testament use of the Greek chilia (thousand). It is part of the broader form of apocalyptic expectation. A core doctrine in some variations of Christian eschatology is the expectation that the Second Coming is very near and that there will be an establishment of a Kingdom of God on Earth. According to an interpretation of prophecies in the Book of Revelation, this Kingdom of God on Earth will last a thousand years (a millennium) or more.
The application of an apocalyptic timetable to the establishment or changing of the world has happened in many cultures and religions, and continues to this day, and is not relegated to the sects of major world religions.
The terms millenarianism and millennialism are sometimes used interchangeably, but this usage is incorrect. As Gould notes:
Millennium is from the Latin mille, "one thousand," and annus, "year"—hence the two n's. Millenarian is from the Latin millenarius, "containing a thousand (of anything)," hence no annus, and no two n's.
Many if not most millenarian groups claim that the current society and its rulers are corrupt, unjust, or otherwise wrong. They therefore believe they will be destroyed soon by a powerful force. The harmful nature of the status quo is considered intractable without the anticipated dramatic change.
Some who held millenarian views were condemned in 1530 by the Lutherans.