Zoroastrianism: A religion from ancient Persia (Iran) that dominated that region prior to the coming of Islam but is today a small minority faith. Named for the prophet Zoroaster (or Zarathustra), whose dates are unknown, Zoroastrianism became the official religion of Persia from the third century B.C. until the seventh century A.D. It is characterized by a *dualism in which Ahura Mazda, the god of light and goodness, struggles to overcome a powerful evil spirit, although contemporary Zoroastrians claim that they are monotheists and do not necessarily see the physical world as bad, as in the ontological dualism of *Manichaeism.
Evans, C. Stephen (2010-04-28). Pocket Dictionary of Apologetics & Philosophy of Religion (p. 125). Intervarsity Press. Kindle Edition.