A similar statement occurs in Yasna 30.3, where the antithesis is however 'aka mainyu', aka being the Avestan language word for "evil." Hence, 'aka mainyu' is the "evil spirit" or "evil mind" or "evil thought," as contrasted with 'spenta mainyu', the "bounteous spirit" with which Ahura Mazda conceived of creation, which then "was."
The 'aka mainyu' epithet recurs in Yasna 32.5, when the principle is identified with the daevas that deceive humankind and themselves. While in later Zoroastrianism, the daevas are demons, this is not yet evident in the Gathas: In Zoroaster's view the daevas are "wrong gods" or "false gods" that are to be rejected, but they are not yet demons.
In Yasna 32.3, these daevas are identified as the offspring, not of Angra Mainyu, but of akem manah, "evil thinking." A few verses earlier it is however the daebaaman, "deceiver" - not otherwise identified but "probably Angra Mainyu" - who induces the daevas to choose achistem manah - "worst thinking." In Yasna 32.13, the abode of the wicked is not the abode of Angra Mainyu, but the abode of the same "worst thinking." "One would have expected [Angra Mainyu] to reign in hell, since he had created 'death and how, at the end, the worst existence shall be for the deceitful' (Y. 30.4)."
In Yasht 19.46ff, Angra Mainyu and Spenta Mainyu battle for possession of khvaraenah, "divine glory" or "fortune". In some verses of the Yasna (eg Yasna 57.17), the two principles are said to have created the world, which contradicts the Gathic principle that declares Ahura Mazda to be the sole creator and which is reiterated in the cosmogony of Vendidad 1. In that first chapter, which is the basis for the 9th-12th century Bundahishn, the creation of sixteen lands by Ahura Mazda is countered by the Angra Mainyu's creation of sixteen scourges such as winter, sickness and vice. "This shift in the position of Ahura Mazda, his total assimilation to this Bounteous Spirit [Mazda's instrument of creation], must have taken place in the 4th century B.C. at the latest; for it is reflected in Aristotle's testimony, which confronts Ariemanios with Oromazdes (apud Diogenes Laertius, 1.2.6)."
Yasht 15.43 assigns Angra Mainyu to the nether world, a world of darkness. So also Vendidad 19.47, but other passages in the same chapter (19.1 and 19.44) have him dwelling in the region of the daevas, which the Vendidad asserts is in the north. There (19.1, 19.43-44), Angra Mainyu is the daevanam daevo, "daeva of daevas" or chief of the daevas. The superlative daevo.taema is however assigned to the demon Paitisha ("opponent"). In an enumeration of the daevas in Vendidad 1.43, Angra Mainyu appears first and Paitisha appears last. "Nowhere is Angra Mainyu said to be the creator of the daevas or their father."
Zurvanism's principle feature is then the notion that both Ahura Mazda (MP: Ohrmuzd) and Angra Mainyu (Ahriman) were twin brothers, with the former being the epitome of good and the latter being the epitome of evil. Further, this dichotomy was by choice, that is, Angra Mainyu chose to be evil: "It is not that I cannot create anything good, but that I will not." And to prove this, he created the peacock.
The mythology of the twins is only attested in the post-Sassanid Syriac and Armenian polemic such as that of Eznik of Kolb. According to these sources the genesis saw Zurvan as existing alone but desiring offspring who would create "heaven and hell and everything in between." Zurvan then sacrificed for a thousand years. Towards the end of this period, androgyne Zurvan began to doubt the efficacy of sacrifice and in the moment of this doubt Ohrmuzd and Ahriman were conceived: Ohrmuzd for the sacrifice and Ahriman for the doubt. Upon realizing that twins were to be born, Zurvan resolved to grant the first-born sovereignty over creation. Ohrmuzd perceived Zurvan's decision, which He then communicated to His brother. Ahriman then preempted Ohrmuzd by ripping open the womb to emerge first. Reminded of the resolution to grant Ahriman sovereignty, Zurvan conceded, but limited kingship to a period of 9000 years, after which Ohrmuzd would rule for all eternity.
In the Book of Arda Viraf 5.10, the narrator - the 'righteous Viraf' - is taken by Sarosh and Adar to see the "the reality of God and the archangels, and the non-reality of Ahriman and the demons." This idea of "non-reality" is also expressed in other texts, such as the Denkard, a 9th century "encyclopedia of Mazdaism", which states Ahriman "has never been and never will be." In chapter 100 of Book of the Arda Viraf, which is titled 'Ahriman', the narrator sees the "Evil spirit, ... whose religion is evil [and] who ever ridiculed and mocked the wicked in hell."
In the Zurvanite Ulema-i Islam (a Zoroastrian text, despite the title), "Ahriman also is called by some name by some people and they ascribe evil unto him but nothing can also be done by him without Time." A few chapters later, the Ulema notes that "it is clear that Ahriman is a non-entity" but "at the resurrection Ahriman will be destroyed and thereafter all will be good; and [change?] will proceed through the will of God." In the Sad Dar, the world is described as having been created by Ohrmuzd and become pure through His truth. But Ahriman, "being devoid of anything good, does not issue from that which is owing to truth." (62.2)
Book of Jamaspi 2.3 notes that "Ahriman, like a worm, is so much associated with darkness and old age, that he perishes in the end." Chapter 4.3 recalls the grotesque legend of Tahmurasp (Avestan: Taxma Urupi) riding Angra Mainyu for thirty years (cf. Yasht 15.12, 19.29) and so preventing him from doing evil. In Chapter 7, Jamasp explains that the Indians declare Ahriman will die, but "those, who are not of good religion, go to hell."
The Bundahishn, a Zoroastrian account of creation completed in the 12th century has much to say about Ahriman and his role in the cosmogony. In chapter 1.23, following the recitation of the Ahuna Vairya, Ohrmuzd takes advantage of Ahriman's incapacity to create life without intervention. When Ahriman recovers, he creates Jeh, the primal whore who afflicts women with their menstrual cycles. In Bundahishn 4.12, Ahriman perceives that Ohrmuzd is superior to himself, and so flees to fashion his many demons with which to meet Creation in battle. The entire universe is finally divided between the Ohrmuzd and the yazads on one side and Ahriman with his devs on the other. Ahriman slays the primal bull, but the moon rescues the seed of the dying creature, and from it springs all animal creation. But the battle goes on, with mankind caught in the middle, whose duty it remains to withstand the forces of evil through good thoughts, words and deeds. Other texts see the world created by Ohrmuzd as a trap for Ahriman, who is then distracted by creation and expends his force in a battle he cannot win. (The epistles of Zatspram 3.23; Shkand Gumanig Vichar 4.63-4.79). The Dadistan denig explains that God, being omniscient, knew of Ahriman's intent, but it would have been against His "justice and goodness to punish Ahriman before he wrought evil [and] this is why the world is created."
Ahriman has no such omniscience, a fact that Ohrmuzd reminds him of (Bundahishn 1.16). In contrast, in Manichean scripture, Mani ascribes foresight to Ahriman.
Haug's interpretation was gratefully received by the Parsis of Bombay, who at the time were under considerable pressure from Christian missionaries (most notable amongst them John Wilson) who sought converts among the Zoroastrian community and criticized Zoroastrianism for its alleged dualism as contrasted with their own monotheism. Haug's reconstruction had also other attractive aspects that seemed to make the religion more compatible with nineteenth-century Enlightenment, as he attributed to Zoroaster a rejection of rituals and of worship of entities other than the supreme deity.
The new ideas were subsequently disseminated as a Parsi interpretation, which eventually reached the west and so in turn corroborated Haug's theories. Among the Parsis of the cities, who were accustomed to English language literature, Haug's ideas were more often repeated than those of the Gujarati language objections of the priests, with the result that Haug's ideas became well entrenched and are today almost universally accepted as doctrine.
While some modern scholars hold views similar to Haug's regarding Angra Mainyu's origins, many now think that the traditional "dualist" interpretation was in fact correct all along and that Angra Mainyu was always considered to be completely separate and independent from Ahura Mazda.
Ahriman's assignment, according to Steiner, is to alienate the human being from his spiritual roots and to inspire materialism and heartless technical control of human activity. His positive contribution is to bring intellectual development and a focus on the sensory world. As such, his influence is highly relevant to present-day Western culture. His great opponent is the archangel Michael, who Steiner equates with Babylonian Marduk. Ahura Mazda and the Vedic Vishva Karman represent Christ's spiritual aura around the Elohim, the spirits of the Sun sphere.