In the second millennium BCE, on the vast Iranian plateau, an ancient religion emerged that would later become famous by the name of its founder, Zarathushtra Spitama. Zoroaster, the ancient prophet of the Iranians, propagated his faith in the eastern region of the Iranian plateau, particularly in the areas of Khwarazm (Khorasan). This religion, later known to the world as Zoroastrianism, is one of the world's first faiths that showed a clear inclination towards monotheism and contained deep philosophical thoughts.
At the core of this religion was the worship of Ahura Mazda, a supreme being called the "Wise Lord." Ahura Mazda was the sole creator of the universe and the source of all goodness, light, and brightness. He was the originator of cosmic order and the law of truth, which is called "Asha" in the Avestan language. Ahura Mazda, timeless and placeless, was the fount of wisdom and benevolence, who watched over all his creations and bestowed goodness and blessing upon the world.
Zoroastrian ontology was based on a fundamental dualism, but not a dualism of two gods. This duality was between two spirits or two intellects that originated from Ahura Mazda: one being Spenta Mainyu, the bounteous spirit or holy intellect, and the other Angra Mainyu, the destructive spirit or evil intellect. Spenta Mainyu symbolized goodness, creation, truth, and light, while Angra Mainyu symbolized evil, destruction, falsehood, and darkness. The battle between these two spirits was a cosmic struggle that flowed through all dimensions of existence.
In this cosmic battle, humanity possessed complete freedom of will and choice. Zoroaster taught his followers that each individual must consciously choose the path of truth, Asha, and stand against the forces of evil with Good Thoughts, Good Words, and Good Deeds (Humata, Hukhta, Hvarshta). This emphasis on individual responsibility and ethical choice was one of the unique features of Zoroastrianism in the ancient world and gave humanity an active role in the destiny of the universe.
In the Zoroastrian faith, there were other important concepts as well. The Amesha Spentas, or "Bounteous Immortals," were six attributes or manifestations of Ahura Mazda that assisted him in governing the world, each symbolizing an aspect of God's existence. Also, the Yazatas, or "Beings Worthy of Worship," were deities who served Ahura Mazda, each being the guardian of an element of nature or an ethical concept. Mithra, the guardian of the covenant, and Anahita, the guardian of water and purity, were among the most important Yazatas.
Fire, in the Zoroastrian faith, was revered as one of the most important symbols. Fire symbolized the light of Ahura Mazda, purity, brightness, and truth, and was kept perpetually burning in Zoroastrian temples. Zoroastrian ceremonies and prayers were often conducted in the presence of fire and with adherence to the principles of physical and spiritual cleanliness. This religion considered life a divine gift and taught humans to protect the elements of nature and strive to increase goodness in the world.
The influence of the Zoroastrian faith on the Iranian kingdoms, especially the Achaemenids, was very deep. This religion emphasized justice, truth, order, and governance based on the will of Ahura Mazda. The Achaemenid kings considered themselves representatives of Ahura Mazda on earth and saw it as their duty to spread peace and justice in the world. These teachings became the ethical foundation of the Achaemenid government and were also reflected in their policies of tolerance.