A Study in the Theology of the Zarathustra's Gathas

The dualism, the belief in the existence of two good and evil power in the world of existence, is one of the ancient Aryan beliefs. In Gathas, the oldest part of the Avesta, dualism emerges as confrontation between twin spirits: Sepanta Mainyu (sacred spirit) opposes to Angra Mainyu (evil spirit). How these two spirits are created is considered as a basic in Zoroastrianism theology and to what extent Ahura-Mazdā is responsible for creation of these two power is one issue that the scholars have different answers for it- some believes that Zoroastrianism is a dualism religion, and others tell that it is a monotheism one. This research by descriptive-analytical method tries to study the ideas of scholars about the creation of evil spirit, oneness or non-oneness of Ahura-Mazdā and the Sacred Spirit, as well as the contradiction of these two spirits. Although ZaraƟuštra identifies Ahura-Mazdā as the supreme god who is the origin of creation, he does not leave the dualistic idea of Aryan beliefs and applies it in his new moral system. Zoroastrianism is monotheism religion in theory but in religious law which is based on the choice of good and evil it is a dualism religion.