Zoroastrianism is an ancient Persian religion teaching cosmic dualism.
It is not known precisely when the ancient Persian religion of Zoroastrianism first came into existence, although scholars generally agree that it first appeared in the late Bronze Age (1500-800 BCE) as a development of Persian polytheism. The sacredness of the bull, for example, entered into Zoroastrianism (and Hinduism also), as did the strong insistence on ritual purification and the holiness of fire (for this reason Zoroastrians never burn their dead, but rather dispose of corpses by “exposing” them to the birds). The dominant religion of Persia until the rise of Islam, Zoroastrianism is now largely confined to the Parsi community of Bombay. Its scriptures are known as the Avesta.
The ancient Persians and Zoroastrians alike also revered asha (in Hinduism rta), a term that is best understood as truth or universal law, especially moral law. Asha was itself upheld by three ahuras, or “good deities”: Varuna, Mithra, and, the most supreme of all, Mazda, the lord of wisdom.
Claiming to be a true prophet of Mazda, Zoroaster, also known as Zarathustra, whose time of life is disputed, taught a form of cosmic dualism, namely, that there are two supreme, morally opposed gods—Ahura Mazda (good) and Angra Mainyu (bad). Zoroaster believed that Ahura Mazda and his ahuras were waging a great war against Angra Mainyu and his devas (evil deities), and that humankind, caught in the middle of this war, should choose to ally himself with Ahura Mazda, not only because Mazda is good but also because Mazda will be ultimately victorious.
Zoroastrianism’s influence lies firstly in itself, which is to say that it is one of the oldest living religions. Beyond this, Zoroastrianism gave Islam its format of five prayers a day, Tibetan Buddhism its practice of corpse exposure, Mahayana Buddhism its world savior concept (Saoshyant, or Maitreya), and Gnosticism and Manichaeism their belief that the world was made by an evil spirit. Zoroastrianism’s apparent influence on Jewish and Christian eschatology, however, has proved difficult to substantiate.