The religion that would become Zoroastrianism belonged to what Jenny Rose describes as "a common linguistic and literary tradition, including that of oral religious poetry, [which] is evidenced in themes, concepts, terminology and the poetic syntax of the Gathas that echo those of the Rig Veda...plac[ing] them initially within an Indo-Iranian continuum, rather than an Ancient Near Eastern mindset.”¹. This linguistic and ideological relationship between Vedic religion and early Zoroastrianism gives insight into a common heritage which allows us to trace the divergence in thought between ancient Iranians and early Indians. Mary Boyce relates the perception of these differences in order to describe the sensibility of each religion: “For a long while it was held that abundance meant a greater tenacity, and that the testimony of the Vedas was to be regarded as superior; but further investigations have shown that in some respects the sparser Avestan [i.e. Iranian] material is more reliable. 'The Vedic evidence is valuable for its richness, the Avestan evidence for its fidelity.'”² Boyce’s comments on the Zoroastrian scriptures or “Avestan material” characterizes the source material for reconstructing the religion of the ancient Iranians as reliable in contributing to our understanding of both the early Zoroastrian and earlier Indo-Iranian religions. In order to parse what commonalities between the Indic Vedas and the Iranian Avesta might reveal in terms of aspects of an earlier Indo-Iranian religion, it is important to take note of the ancient relationship between what would become one of the modern world's few 'major' polytheistic religions and what was one of the two 'major' monotheistic religions of the ancient world.

It is beyond the scope of this investigation to delve too deeply into the complex and fascinating relationship between the Zoroastrian and Hindu traditions, but it is important to acknowledge how this connection informs our understanding of the lineage of development from the Indo-Iranian religion, through the ancient Iranian religion, to Zoroastrianism. Boyce describes the influential legacy of the Indo-Iranian religious heritage,

Many divine beings are honoured in the Avesta, and probably the original pantheon of Iranian gods is very largely represented there...a few of the greatest were worshipped also by the Vedic Indians. These particular divinities must have been venerated for countless generations by the Indo-Iranians in their nomad days for their cults to have survived in this manner long after the two peoples had parted and made their slow ways to new and very different homes...³

If the roots of the pre-Iranian religion are as strong as Boyce describes, then it would seem a great feat indeed to throw off such polytheism for monotheistic innovation. It seems more likely that there existed in that Indo-Iranian religion the seed of a sort of proto-monotheism which, in the case of the ancient Iranians was allowed development in the time after the two groups diverged, but perhaps, in the case of the Indians, was not given the same expression as they crossed the Indus River Valley.

In order to shed light on the formative influence of this proto-monotheism, we must consider two specific aspects of the Zoroastrian expression of monotheism which differentiate it from that of Judaism: the first, as described by Rose, is "...a system of ethical and cosmological opposition...”⁴; the second, as Boyce puts it, is that "the ancient...asuras [gods] all personify abstract concepts.”⁵. Many of these aspects have clear roots in the Indo-Iranian religion and while the first understanding of Zoroastrian monotheism has been dismissed by some biblical scholars as a dualism which undermines the power of a singular deity⁶, the second expression appears closely connected to modern (Christian) conceptions of 'high monotheism'.⁷ Although we might identify each of these concepts with some biblical analogue, as I have here, such interpretations appear as a clunky and reductionist attempt to distill the intricate worldview to which they belong.

It is important to consider each of these aspects a bit further in order to understand both the Zoroastrian expression of monotheism and the indelible marks of its early Indo-Iranian heritage on such an expression. Perhaps the most concise example of an Indo-Iranian deity from which we can understand this construction of abstract-concept-as-god is Mitra. Indologist Paul Thieme writes: “Mitra turns out to be...not a god of the sun or some other phenomenon of nature, conceived as a divinity, but the personification of this sacred concept 'contract, treaty,' designated in the Rigveda and in the Avesta by the appellative noun mitra-/miӨra-.”⁸ In contrast to the Mesopotamian sun-god Shamash, who eventually came to be the god of justice as well⁹, Mitra is the power of the contract, bond, or treaty. This construction brings to mind assertions for the 'natural' dominance of 'higher monotheism' made by such early religious theorists as Tylor and Frazer.¹⁰ Boyce suggests as much in her comment that “...the high gods of the Indo-Iranians already resembled the Deity of monotheistic religions, and foreshadowed in their greatness the dignity of Zoroaster's own concept of the supreme Lord.”¹¹ This is key to understanding that Indo-Iranian and ancient Iranian religions served as more than just loose inspiration in the lineage of the development of Zoroastrianism: it was the core which directly informed the ideological distillations and innovations that were spun around it.

Another Indo-Iranian concept, that of “cosmological opposition,” which can poorly be described in western terms of 'good vs. evil', reflects the construction of what Boyce describes as “...a universal principle of what ought to be, [in Avestan] 'asha', [in Sanskrit] 'rta', variously translated as 'order, righteousness, truth'.”¹² This idea underlies the framework of both Zoroastrian and Vedic religion, but Rose outlines how the understanding of the concept then developed differently within the two emerging religions:

In the Gathas the opposite of asha is not a simple negation, such as is the case with Rig Vedic anrta. The contrary ethos to asha is druj – the deception that brings chaos to the good, ordered creations of Ahura Mazda. Druj confuses the true nature of the working of the world, so that one is unable to make the right choices, as did the daevas, the unnamed ‘false or erroneous gods’, who, in confusion, made bad choices in opposition to asha. Druj is usually translated as ‘the Lie’ in the sense of a deception or a misrepresentation of reality.¹³

If we are to attempt to interpret this religious construction, the “cosmological opposition” is better described in terms of 'truth vs. lie' rather than 'good vs. evil'. It is cogent to this discussion to suggest a dissociation between this opposition, of asha and druj, and what theologian Patrick D. Miller calls “[t]he conflict between the 'children of light' and the 'children of darkness' in apocalyptic thinking...”¹⁴ Commenting on the effects of such dualism in the Israelite religion, he suggests that this conflict “...was a further indication of an incipient dualistic way of thinking that served to undermine the integration of divine power in Yahweh of Israel without, however, fully undoing it.”¹⁵ While Miller's comments might well apply to dualism in a biblical context, the ancient Iranian concept of opposition could support the integrative power of the singular deity of Zoroastrianism.¹⁶ It seems more likely, given the historical penchant of humans for religious syncretism, that the integration of multiple deities into one would seem facilitated by a structure which would identify unwanted religious activities as 'false' or 'lie' rather than 'evil'. This concept lends itself readily to the language used in expressing the regard of one religious group to another: one may not regard the religion to which one does not adhere as 'evil' but as 'false' relative to one's own 'true' religion. This is one connection between Zoroastrianism and its antecedent Iranian religion which cannot be dismissed as unrelated to the direct development of the former from the latter. In order to understand another connection, we must explore the significance of constructing deities of abstract concepts.

The process which occupies our current discussion is that which lead from the apparently (numerically) polytheistic religious system of the Indo-Iranians and ancient Iranians to the expression of monotheism in Zoroastrianism. It is a reasonable step from Boyce's suggestion that the “...high gods of the Indo-Iranians already resembled the Deity of monotheistic religions...”¹⁷ to conceiving of a monotheistic worldview, which characterized the pre-Zoroastrian religion of the ancient Iranians, that directly facilitated the development of the specific monotheism of followers of Zarathushtra. Like Mitra, the name and conception of the supreme deity of Zoroastrianism is fixed in the abstract:

Mazda is a cognate agent noun from the compound man + dā, and is most accurately translated as 'the one who keeps mental track' or 'the one who is wise/knowledgeable'. The other epithet that often appears alongside mazda in the Gathas is ahura. One etymology for ahura is from a verb meaning 'to engender'. The most accurate translation of the two-part name Ahura Mazda is 'Wise Lord'.¹⁸

Boyce speculates that the specific religious focus on Ahura Mazda is deep rooted in the Indo-Iranian religion and it is this worship that continued throughout the ancient Iranian religion directly into modern Zoroastrianism.¹⁹ Boyce observes: “It seems therefore that in pagan days Mazdā was so regularly spoken of and invoked with his own name and the title Ahura that these became fused together in time to form a single appellation.”²⁰ Thus it is not difficult to plot the trajectory of a stable conception of this deity from the ancient Iranian religion to Zoroastrianism and would suggest that whatever worldview contextualized the construction of Ahura Mazda in the former religion could not have been so foreign to the latter. It is the apparent 'organic' development from one religion to the other that suggests the implausibility of a narrative of a monotheistic Zarathustra 'overthrowing' the polytheism of the ancient Iranian religion.