zoroastrianism
Zo`ro*as"tri*an*ism, n. Defn: The religious system of Zoroaster, the legislator and prophet of the ancient Persians, which was the national faith of Persia; mazdeism. The system presupposes a good spirit (Ormuzd) and an opposing evil spirit (Ahriman). Cf. Fire worship, under Fire, and Parsee.