Dualism or dualism is one of the challenging doctrines that from the perspective of the common people means dualism and is considered only related to the Zoroastrian religion in ancient Iran. While this doctrine has a deeper meaning than dualism in the field of theology and ontology, and on the other hand, this doctrine is also observed in the two ancient religions of Hinduism and Daoism in the two great civilizations of India and China, in addition to Zoroastrianism. However, considering the difference in the theological and ontological foundations of these great religions, dualism has completely different definitions in these religions, which have nothing in common except the dualism of the origin of existence. In fact, when we encounter the term dualism in these religions, we should note that the basis of dualism in these religions is completely different; As in Zoroastrianism, duality means the opposition of the principle of good (Spanthamino) and evil (Angarhamino), in the Sankhya and Yoga schools, in Hinduism it means the cooperation of the two principles of creation, spirit (Purusha) and matter (Prakriti), and in Taoism it means balance in existence based on the two opposing and complementary forces of Yin and Yang. This article attempts to explain duality in these ancient religions, as well as to compare and contrast the foundations of this doctrine in these religions and point out its similarities and differences.