Zurvanism is a now-extinct branch of Zoroastrianism that had the divinity Zurvan as its First Principle (primordial creator deity). Zurvanism is also known as Zurvanite Zoroastrianism.

In Zurvanism, Zurvan is the god of infinite time (and space) and is aka (“one", "alone”) deity of matter. Zurvan is the parent of the two opposites representing the good god Ahura Mazda and the evil Angra Mainyu. Zurvan is regarded as a neutral god, being without gender (neuter), without passion, and one for whom there is no distinction between good or evil. Zurvan is also the god of destiny, light and darkness. Zurvan is a normalized rendition of the word, which in Middle Persian appears as either Zurvān, Zruvān or Zarvān. The Middle Persian name derives from Avestan zruvan-, "time" or "old age".

Zurvanites considered Ahura Mazda and Spenta Mainyu one of two equal-but-separate divinities under the primacy of Zurvan. The central Zurvanite belief made Ahura Mazda the middle god and Angra Mainyu the fallen twin brother. Mazdeans consider the divinity of Ahura Mazda the transcendental creator.

Origins and background

Although the details of the origin and development of Zurvanism remain murky (for a summary of the three opposing opinions, see Ascent and acceptance below), it is generally accepted that Zurvanism was a branch of greater Zoroastrianism (Boyce 1957:157-304); that the doctrine of Zurvan was a sacerdotal response to resolve a perceived inconsistency in the sacred texts (Zaehner, 1955, intro; See development of the "twin brother" doctrine below); and that this doctrine was probably introduced during the second half of the Achaemenid era (Henning, 1951; loc. Cit. Boyce 1957:157-304).

Zurvanism enjoyed royal sanction during the Sassanid era (226-651 CE) but no traces of it remain beyond the 10th century. Although Sassanid era Zurvanism was certainly influenced by Hellenic philosophy, whether Zoroastrian Zurvan was an adaptation of an antecedent or alien divinity of Time (Greek Chronos) has not been conclusively established.

Non-Zoroastrian accounts of typically Zurvanite beliefs were the first traces of Zoroastrianism to reach the west, leading European scholars to conclude that Zoroastrianism was a monist religion, an issue of much controversy among both scholars and contemporary practitioners of the faith.

Iranian Zurvan is related to the Sanskrit word Sarva and carries a similar semantic field in describing monistic deity.