Douglas Harper's Etymology Dictionary
1906, from millennial + -ism.
Wiktionary
n. millenarianism
Wikipedia
Millennialism (from millennium, Latin for "thousand years"), or chiliasm in Greek, is a belief held by some Christian denominations that there will be a Golden Age or Paradise on Earth in which "Christ will reign" for 1000 years prior to the final judgment and future eternal state (the " World to Come" of the New Heavens and New Earth). This belief is derived primarily from . Millennialism is a specific form of millenarianism.
Similarities to millennialism are found in Zoroastrianism. It held that there were 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 (supposed by some to be the year 2000). "Then Saoshyant makes the creatures again pure, and the resurrection and future existence occur" (Zand-i Vohuman Yasht 3:62).
Various other social and political movements, both religious and secular, have also been linked to millennialist metaphors by scholars.
Usage examples of "millennialism".
Broadway's flirtation with millennialism had been brief, but the rest of the world was less jaded.