Millenarian

From Late Latin millenarius + -an.

Full definition of millenarian

(Christianity) Pertaining to the belief in an impending period of one thousand years of peace and righteousness associated with the Second Coming of Christ. from 17th c.

2009, Diarmaid MacCulloch, A History of Christianity, Penguin 2010, p. 699:Franciscans coming from Iberia were particularly prone to the millenarian enthusiasm which gripped southern Europe around 1500, and which the Franciscan Order had so long fostered. They believed that they were living in the End Times ....
2011, Thomas Penn, Winter King, Penguin 2012, p. 108:Mirandola cultivated a Dominican friar, Savonarola, whose millenarian visions had provoked revolution: in the wake of France's invasion, he had inspired a popular uprising in Florence, its ruling Medici family replaced by a people's republic.

Pertaining to any of various religious or social movements which believe in a coming radical change to existing world order; utopian, apocalyptic. from 20th c.
Lasting or expected to last a thousand years.

1994, in the Catalan Review, volume 8, page 222:... contrasts with the rapid decline and demise of the millenarian empire of Byzantium.
1997, Olivier ClÃ©ment, Conversations with Ecumenical Patriarch Bartholomew I, page 159:But the ashes of Auschwitz fell on Hitler's folly, on the announcement of the millenarian Reich.
2006, in the Journal of Middle Eastern geopolitics, volume 1:In a few years, by fueling a sense of regained confidence within its own people, which suffered from the fall of a millenarian empire, Ataturk managed to readapt Turkish traditions in the framework of a new model of state.

(plural millenarians)