Angra Mainyu or Ahriman was the "evil spirit" in the dualistic strain of Zoroastrianism. Angra Mainyu is the adversary of Ahura Mazda, the god of good.
The name does not occur in the Old Persian inscriptions. In the Avesta he is called the twin-brother of the Holy Spirits, and contrasted either with the Holy Spirit of Ahura Mazda or with Ahura Mazda himself. He is the all-destroying Satan, the source of all evil in the world and, like Ahura Mazda, exists since the beginning of the world. Ahriman chose evil consciously, and by this act he created death. Eventually, in the great world catastrophe, he will be defeated by Ahura Mazda and disappear. The later sect of the Zurvanites held that both were visible manifestations of the primeval principle zruvan akarana (infinite time).
The central subject of Zoroastrian teaching and theology is the constant ongoing battle between Angra Mainyu and Ahura Mazda.
Ahriman is held by many to be the source of the Judeo-Christian belief in Satan as being the chief agent of evil. Before the Babylonian captivity Judaism held the belief that Satan was an agent of God and that he tested mans loyalty to God. After that captivity Satan became God's rival, and the lord of evil. It is believed that the Israelites may have encountered Zoroastrianism by being freed by the Persians under Cyrus the Great and that this view of Ahriman changed their belief in Satan and made Satan into the enemy of God.
- Wikipedia. (2005). Angra Mainyu (http://en.wikipedia.org/wiki/Angra_Mainyu). Retrieved on July 14. 2005.