Menu Ethical Dualism - Good v/s Evil 4020.12

Because of its emphasis on the persistent conflict between the forces of good and evil, Zoroastrianism is distinguished from monotheistic frameworks that recognize only one power as supreme. So, Zoroastrianism is not theologically content with accepting the monotheistic idea that the evil forces in the universe are simply another aspect of the supreme being's creations. Mardanfarrokh, a Zoroastrian theologian in the ninth century C.E., noted that if evil were to come from God along with everything else, his perfection would be mitigated.
According to Mardanfarrokh, therefore, only human choice can determine the intensity of evil within the world, a teaching which removes responsibility for evil from Ahura Mazda and renders the system dualistic. Good and evil, rather than deriving from the same source in Ahura Mazda, are separated on the grounds of moral choice, an idea which has lead scholars to refer to Zoroastrianism as "ethical dualism," in that all decisions made by human beings follow either the good path of the Wise Lord or the evil path of Angra Mainyu.
The nature of the two opposing spirits of good and evil results from the choice they made between asha ("truth") and druj ("lie"). Spenta Mainyu chose asha, and Angra Mainyu chose druj, and now each human must choose one of these paths for themselves. No force in the Heavens and Earth has the power to force a person to do evil, and the rewards, punishments, happiness, and grief an individual receive depends on how he or she lives his or her life. As the aggregate of human decisions steers humanity away from evil, the Ahuric creation is enhanced and the world as we know it, replete with evil, will dissolve away. Thus, Zoroastrian dualism affirms the freedom and importance of human choice in the metaphysic structure of the universe.
From
Newworldencyclopedia .com