Zoroastrianism was founded by Zarathushtra (Zoroaster) in Persia which followed an aboriginal polytheistic religion at the time. He preached what may have been the first monotheism with a single supreme god, Ahura Mazda. Zoroastrians belief in the dualism of good and evil as either a cosmic one between Ahura Mazda and an evil spirit of violence and death, Angra Mainyu, or as an ethical dualism within the human consciousness. The Zoroastrian holy book is called the Avesta which includes the teachings of Zarathushtra written in a series of five hymns called the Gathas. They are abstract sacred poetry directed towards the worship of the One God, understanding of righteousness and cosmic order, promotion of social justice, and individual choice between good and evil. The rest of the Avesta was written at a later date and deals with rituals, practice of worship, and other traditions of the faith.

Zoroastrians worship through prayers and symbolic ceremonies that are conducted before a sacred fire which symbolizes their God. They dedicate their lives to a three-fold path represented by their motto: "Good thoughts, good words, good deeds." The faith does not generally accept converts but this is disputed by some members.