Zoroastrianism, or Mazdayasna, is one of the world's oldest religions that remains active. It is a monotheistic faith (i.e. a single creator god), centered in a dualistic cosmology of good and evil and an eschatology predicting the ultimate destruction of evil. Ascribed to the teachings of the Iranian-speaking prophet Zoroaster (also known as Zarathustra), it exalts a deity of wisdom, Ahura Mazda (Wise Lord), as its Supreme Being. Major features of Zoroastrianism, such as messianism, judgment after death, heaven and hell, and free will have influenced other religious systems, including Second Temple Judaism, Gnosticism, Christianity, Islam, and Buddhism.
With possible roots dating back to the second millennium BCE, Zoroastrianism enters recorded history in the 5th-century BCE. Along with a Mithraic Median prototype and a Zurvanist Sassanid successor, it served as the state religion of the pre-Islamic Iranian empires for more than a millennium, from around 600 BCE to 650 CE. Zoroastrianism was suppressed from the 7th century onwards following the Muslim conquest of Persia of 633–654. Recent estimates place the current number of Zoroastrians at around 190,000, with most living in India and in Iran; their number is declining. In 2015, there were reports of up to 100,000 converts in Iraqi Kurdistan. Besides the Zoroastrian diaspora, the older Mithraic faith Yazdânism is still practised amongst Kurds.
The most important texts of the religion are those of the Avesta, which includes the writings of Zoroaster known as the Gathas, enigmatic poems that define the religion's precepts, and the Yasna, the scripture. The full name by which Zoroaster addressed the deity is: Ahura, The Lord Creator, and Mazda, Supremely Wise. The religious philosophy of Zoroaster divided the early Iranian gods of Proto-Indo-Iranian tradition, but focused on responsibility, and did not create a devil per se. Zoroaster proclaimed that there is only one God, the singularly creative and sustaining force of the Universe, and that human beings are given a right of choice. Because of cause and effect, they are responsible for the consequences of their choices. The contesting force to Ahura Mazda was called Angra Mainyu, or angry spirit. Post-Zoroastrian scripture introduced the concept of Ahriman, the Devil, which was effectively a personification of Angra Mainyu.
Zoroastrianism's creator Ahura Mazda, through the Spenta Mainyu (Good Spirit, "Bounteous Immortals") is an all-good "father" of Asha (Truth, "order, justice"), in opposition to Druj ("falsehood, deceit") and no evil originates from "him". "He" and his works are evident to humanity through the six primary Amesha Spentas and the host of other Yazatas, through whom worship of Mazda is ultimately directed. Spenta Mainyu adjoined unto "truth", oppose the Spirit's opposite, Angra Mainyu and its forces born of Akəm Manah ("evil thinking").
Zoroastrianism has no major theological divisions, though it is not uniform; modern-era influences having a significant impact on individual and local beliefs, practices, values and vocabulary, sometimes merging with tradition and in other cases displacing it. In Zoroastrianism, the purpose in life is to "be among those who renew the world...to make the world progress towards perfection". Its basic maxims include: