Zoroastrianism or Mazdayasna is one of the world's oldest continuously practiced religions, based on the teachings of the Iranian-speaking prophet Zoroaster (also known as Zaraθuštra in Avestan or Zartosht in Modern Persian).[1][2] Zoroastrianism has a dualistic cosmology of good and evil and an eschatology which predicts the ultimate conquest of evil by good.[3] Zoroastrianism exalts an uncreated and benevolent deity of wisdom, Ahura Mazda (Wise Lord), as its supreme being.[4] The unique historical features of Zoroastrianism, such as its monotheism,[5][6][7][8][9] messianism, judgment after death, heaven and hell, and free will may have influenced other religious and philosophical systems, including Second Temple Judaism, Gnosticism, Greek philosophy,[10] Christianity, Islam,[11] the Baháʼí Faith.

With possible roots dating back to the Second Millennium BCE, Zoroastrianism enters written history in the 5th century BCE.[12] It served as the state religion of the ancient Iranian empires for more than a millennium, from around 600 BCE to 650 CE, but declined from the 7th century CE onwards following the Muslim conquest of Persia of 633–654 and subsequent persecution of the Zoroastrian people.[13] Recent estimates place the current number of Zoroastrians at around 110,000–120,000[14] at most, with the majority living in India, Iran, and North America; their number has been thought to be declining.[15][16]

The most important texts of the religion are those contained within the Avesta, which includes as central the writings of Zoroaster known as the Gathas, poems within the Yasna that define the teachings of the Zoroaster, the main worship service of Zoroastrianism. The religious philosophy of Zoroaster divided the early Iranian gods of the Proto-Indo-Iranian tradition into ahuras[17] and daevas,[18] the latter of which were not considered worthy of worship. Zoroaster proclaimed that Ahura Mazda was the supreme creator, the creative and sustaining force of the universe through Asha,[4] and that human beings are given a choice between supporting Ahura Mazda or not, making them responsible for their choices. Though Ahura Mazda has no equal contesting force, Angra Mainyu (destructive spirit/mentality), whose forces are born from Aka Manah (evil thought), is considered the main adversarial force of the religion, standing against Spenta Mainyu (creative spirit/mentality).[19] Middle Persian literature developed Angra Mainyu further into Ahriman and advancing him to be the direct adversary to Ahura Mazda.[20]

In Zoroastrianism, Asha (truth, cosmic order), the life force that originates from Ahura Mazda,[4][21] stands in opposition to Druj (falsehood, deceit)[22][23] and Ahura Mazda is considered to be all-good with no evil emanating from the deity.[4] Ahura Mazda works in gētīg (the visible material realm) and mēnōg (the invisible spiritual and mental realm)[24] through the seven (six when excluding Spenta Mainyu) Amesha Spentas[25] (the direct emanations of Ahura Mazda).

Zoroastrianism is not entirely uniform in theological and philosophical thought, especially with historical and modern influences having a significant impact on individual and local beliefs, practices, values and vocabulary, sometimes merging with tradition and in other cases displacing it.[26] In Zoroastrianism, the purpose in life is to become an ashavan (a master of Asha) and to bring happiness into the world, which contributes to the cosmic battle against evil. Zoroastrianism's core teachings include:

  • Follow the Threefold Path of Asha: Humata, Huxta, Huvarshta (Good Thoughts, Good Words, Good Deeds).[27]
  • Charity is a way of keeping one's soul aligned with Asha and thus of spreading happiness.[28]
  • The spiritual equality and duty of men and women alike.[29]
  • Being good for the sake of goodness and without the hope of reward (see Ashem Vohu).