Zoroastrianism, ancient pre-Islamic religion of Iran that survives there in isolated areas and, more prosperously, in India, where the descendants of Zoroastrian Iranian (Persian) immigrants are known as Parsis, or Parsees.

The Iranian prophet and religious reformer Zarathushtra (flourished before the 6th century bce)—more widely known outside Iran as Zoroaster (the Greek form of his name)—is traditionally regarded as the founder of the religion.

Zoroastrianism contains both monotheistic and dualistic features.

It likely influenced the other major Western religions—Judaism, Christianity, and Islam. For a discussion of the context in which Zoroastrianism arose, see ancient Iranian religion.

                    Nature and Significance

The ancient Greeks saw in Zoroastrianism the archetype of the dualistic view of the world and of human destiny. Zarathushtra was supposed to have instructed Pythagoras in Babylon and to have inspired the Chaldean doctrines of astrology and magic.

It is likely that Zoroastrianism influenced the development of Judaism and the birth of Christianity. The Christians, following a Jewish tradition, identified Zoroaster with Ezekiel, Nimrod, Seth, Balaam, and Baruch and even, through the latter, with Jesus Christ himself.

On the other hand, as the presumed founder of astrology and magic, Zarathushtra could be considered the arch-heretic.

Though Zoroastrianism was never, even in the thinking of its founder, as insistently monotheistic as, for instance, Judaism or Islam, it does represent an original attempt at unifying under the worship of one supreme god a polytheistic religion comparable to those of the ancient Greeks, Latins, Indians, and other early peoples.

Its other salient feature, namely dualism, was never understood in an absolute, rigorous fashion. Good and evil fight an unequal battle in which the former is assured of triumph.

God’s omnipotence is thus only temporarily limited. In this struggle all human beings must enlist because of their capacity for free choice.

They do so with soul and body, not against the body, for the opposition between good and evil is not the same as the one between spirit and matter.

Contrary to the Christian or Manichaean (from Manichaeism—a Hellenistic dualistic religion founded by the Iranian prophet Mani) attitude, fasting and celibacy are proscribed except as part of the purificatory ritual.

The human struggle has a negative aspect, nonetheless, in that it must strive for purity and avoid defilement by the forces of death, contact with dead matter, etc.

Thus, Zoroastrian ethics, though in itself lofty and rational, has a ritual aspect that is all-pervading. On the whole, Zoroastrianism is optimistic and has remained so even through the hardship and oppression of its believers.

                 Pre-Zoroastrian Persian Religion

The religion of Iran before the time of Zarathushtra is not directly accessible, for there are no reliable sources more ancient than those composed by or attributed to the prophet himself.

It has to be studied indirectly on the basis of later documents and by a comparative approach.

The language of Iran is closely akin to that of northern India, and, hence, the people of the two lands probably had common ancestors who spoke a common Indo-Aryan language.

The religion of those peoples has been reconstructed by means of common elements contained in the sacred books of Iran and India, mainly the Avesta and the Vedas.

Both collections exhibit the same kind of polytheism with many of the same gods, notably the Indian Mitra (the Iranian Mithra), the cult of fire, sacrifice by means of a sacred liquor (soma in India, in Iran haoma), and other parallels.

There is, moreover, a list of Indo-Iranian gods in a treaty concluded about 1380 bce between the Hittite emperor and the king of Mitanni. The list includes Mitra and Varuna, Indra, and the two Nāsatyas.

All of these gods also are found in the Vedas but only the first one in the Avesta, except that Indra and Nāñhaithya appear in the Avesta as demons; Varuna may have survived under another name.

Important changes, then, must have taken place on the Persian/Iranian side, not all of which can be attributed to the prophet.

The Indo-Iranians appear to have distinguished from among their gods the daiva (Indo-Iranian and Old Persian equivalent of Avestan daeva and Sanskrit deva, related to the Latin deus), meaning heavenly, and the asura, a special class with occult powers.

This situation was reflected in Vedic India; later on, asura came to signify, in Sanskrit, a kind of demon, because of the baleful aspect of the asura’s invisible power.

In Iran the evolution must have been different: the ahuras were extolled to the exclusion of the daevas, who were reduced to the rank of demons.

                 The Reformation of Zarathushtra

Zarathushtra (Zoroaster) was a priest of a certain ahura (Avestan equivalent of Sanskrit asura) with the epithet mazdā, wise, whom Zarathushtra mentions once in his hymns with the [other] ahuras.

Similarly, Darius I (522–486) and his successors worshipped Auramazda (Ahura Mazdā) and the other gods who exist or Ahura Mazdā, the greatest god.

The two historically related facts are evidently parallel: on both sides the rudiments of monotheism are present, though in a more elaborate form with the prophet Zarathushtra.

It has not yet been possible to place Zarathushtra’s hymns, the Gāthās, in their historical context. Not a single place or person mentioned in them is known from any other source.

Vishtāspa, the prophet’s protector, can only be the namesake of the father of Darius, the Achaemenid king.

All that may safely be said is that Zarathushtra lived somewhere in eastern Iran, far from the civilized world of western Asia, before Persia became unified under Cyrus II the Great.

If the Achaemenids ever heard of him, they did not see fit to mention his name in their inscriptions nor did they allude to the beings who surrounded the great god and were later to be called the amesha spentas, or bounteous immortals—an essential feature of Zarathushtra’s doctrine.

Religion under the Achaemenids was in the hands of the Magi, whom the Greek historian Herodotus describes as a Median tribe with special customs, such as exposing the dead, fighting evil animals, and interpreting dreams.

Again, the historical connection with Zarathushtra—whom Herodotus also ignores—is a hazy one. It is not known when Zarathushtra’s doctrine reached western Iran, but it must have been before the time of Aristotle (384–322), who alludes to its dualism.

Darius, when he seized power in 522, had to fight a usurper, Gaumata the Magian, who pretended to be Bardiya, the son of Cyrus the Great and brother of the king Cambyses.

This Magian had destroyed cultic shrines, āyadanas, which Darius restored. One possible explanation of these events is that Gaumata had adopted Zoroastrianism, a doctrine that relied on the allegiance of the common people, and therefore destroyed temples or altars to deities of the nobility.

Darius, who owed his throne to the support of some noblemen, could not help favoring their cult, though he adopted Auramazda as a means of unifying his empire.

Xerxes, successor to Darius, mentioned in one of his inscriptions how at a certain (unnamed) place he substituted the worship of Auramazda for that of the daivas, which does not mean that he opposed the daeva cult as such.

Like what a true Zoroastrian would have done, but only that he eradicated somewhere—probably in Babylon—the cult of deities alien to the religion of the ahuras.

It points to a change of attitude, compared with Cyrus’s tolerance of alien religions, such as the Babylonian or the Jewish religion.

From Artaxerxes II (404–359/358) onward, the inscriptions mention, besides Auramazda, Mithra and the goddess Anahita (Anahit), which proves only a change of emphasis, not the appearance of new deities.

                              The Arsacid Period

In consequence of Alexander’s conquest, the Iranian religion was almost totally submerged by the wave of Hellenism.

At Susa, for instance, which had been one of the capital cities of the Achaemenids but where the religion of Auramazda was not indigenous, the coinage of the Seleucid and Arsacid periods does not represent a single Iranian deity.

Then the Iranian religion gradually emerged again. In Commagene in the middle of the 1st century bce, gods bear combinations of Greek and Iranian names: Zeus Oromazdes, Apollo Mithra, Helios Hermes, Artagnes Herakles Ares.

The first proof of the use of a Zoroastrian calendar, implying the official recognition of Zoroastrianism, is found some 40 years earlier at Nisa (near modern Ashgabat in Turkmenistan).

By then some form of orthodoxy must have been established in which Auramazda and the entities (powers surrounding him) adjoin other gods such as Mithra, the Sun, and the Moon.

In Persis (modern Fārs), from the beginning of the Christian Era to the advent of the Sasanians (early 3rd century Ce), any allusion to the fire cult disappears.

The coins seem to indicate, in not showing the fire altar, that the prince had lost interest in the Persian/Iranian religion.

                    The Sasanian Period

With Ardashīr, the future founder of the Sasanian dynasty, the situation was different, and this may suggest that his religious zeal—as a hereditary priest of Staxr (Istaxr)—may have helped him seize power in his native province, even before he started attacking his Arsacid suzerain, Artabanus V.

Two persons are recorded, in different sources, as helping to establish Zoroastrianism under the first Sasanians: Kartēr and Tansar.

Whereas Kartēr is known through contemporary inscriptions, most of which were written by himself, Tansar (or Tosar) is only remembered in later books.

The latter tell us that Tansar, an ehrpat, or theologian, undertook the task, under Ardashīr’s command, of collecting the sacred texts and fixing the canon.

Kartēr, who was already active under Ardashīr I but more so under Shāpūr and his successors, recounted his brilliant career, which reflects the birth of a hierarchy.

He was still an ehrpat under Shāpūr, as he restored the Mazdean religion…in the land of non-Iran reached by the horses and men of the king of kings.

Under Hormizd he was made Ormazd’s magupat, a term apparently created for him and meaning chief of the Magians of Auramazda.

Under Bahrām I (273–276), Mani, the founder of Manichaeism, who had enjoyed a degree of tolerance under the two preceding kings, was sacrificed to the interests of Zoroastrianism and died in prison.

Bahrām II named Kartēr Savior of the Soul of Bahrām, elevated him to the rank of the grandees of the realm, and gave him the additional titles of judge of the empire, master of rites, and ruler of the fire of Anahit-Ardashīr at Staxr and of Anahit the Dame.

Promoted to the apex of his career, Kartēr persecuted Jews, Buddhists, Brahmins, Nasoreans [Judeo-Christians?], Christians, Maktaks [Mandeans, Manichaeans?], and Zandīks [Mazdean heretics].

Narses (293–302), who began his struggle for power when Bahrām II was still on the throne, seems to have recovered the title of chief of the Staxr temple that his predecessor and adversary had surrendered to Kartēr.

Under Shāpūr II, the high priest Aturpāt, at a council summoned to fix the text of the Avesta, proved the truth of his doctrine by submitting to the ordeal of molten metal poured on his breast and was victorious over all kinds of sectarians and heretics.

Under Bahrām V (420–438), presumably, the title magupatān magupat (chief magus of the chief magi) was created. Under Qobād (or Kavādh; 488–496 and 498/499–531), Iran traversed its gravest social and religious crisis under the impact of Mazdak.

This reformer, whose doctrines were partly inspired by those of Mani, was granted an interview by Qobād—as Shāpūr I had received Mani a long time before, but with a more decisive success.

Perhaps the king hoped that by abolishing property and the family he would reign over a docile mass. The Mazdakites favored the abolition of all social inequalities, chiefly of private property, the main cause of all hatred.

Everything was to be held in common, including women. These views directly threatened the rich as well as the Mazdean clergy, who soon understood this.

Qobād was dethroned and replaced by his brother Jāmāsp. After two years in exile, Qobād recovered his throne, but he had been cured of his egalitarian views and decided to liquidate the Mazdakites.

Khosrow I continued the work of his father, Qobād, and thus the Mazdakite upheaval made way for a strong state and an established Mazdean Church.

The religious books give Khosrow the unique title of anōshirvan, with the immortal soul, probably for having crushed Mazdakism and for enabling the good religion to triumph.

Khosrow II (590/591–628) married a Christian woman and showed sympathy toward his Christian subjects. He was superstitious and dabbled in astrology.

                  Founding of Islam and Arab conquest of Persia

The Muslim conquest of Persia (also known as the Arab conquest of Iran led to the end of the Sasanian Empire in 651 and the eventual decline of the Zoroastrian religion in Iran.

Arabs first attacked the Sassanid territory in 633, when general Khalid ibn Walid invaded Mesopotamia (what is now Iraq), which was the political and economic center of the Sassanid state.

Following the transfer of Khalid to the Roman front in the Levant, the Muslims eventually lost their holdings to Iranian counterattacks.

The second invasion began in 636 under Saad ibn Abi Waqqas, when a key victory at the Battle of Qadisiyyah led to the permanent end of Sasanian control west of Iran.

The Zagros mountains then became a natural barrier and border between the Rashidun Caliphate and the Sassanid Empire.

Owing to continuous raids by Persians into the area, Caliph Umar ordered a full invasion of the Sasanian Iranian empire in 642, which was completed with the complete conquest of the Sasanians around 651.

The quick conquest of Iran in a series of well-coordinated multi-pronged attacks directed by Caliph Umar from Medina, several thousand kilometers from the battlefields in Iran, became his greatest triumph, contributing to his reputation as a great military and political strategist.

Iranian historians have sought to defend their forebears by using Arab sources to illustrate that contrary to the claims of some historians, Iranians, in fact, fought long and hard against the invading Arabs.

By 651, most of the urban centers in Iranian lands, with the notable exception of the Caspian provinces and Transoxiana, had come under the domination of the Arab armies.

Many localities in Iran staged a defense against the invaders, but in the end none was able to repulse the invasion.

Even after the Arabs had subdued the country, many cities rose in rebellion, killing the Arab governor or attacking their garrisons, but reinforcements from the caliphs succeeded in putting down all these rebellions and imposing the rule of Islam.

The violent subjugation of Bukhara after many uprisings is a case in point. Conversion to Islam was, however, only gradual. In the process, many acts of violence took place, Zoroastrian scriptures were burnt and many mobads executed.

Once conquered politically, the Persians began to reassert themselves by maintaining Persian language and culture. Regardless, Islam was adopted by many – for political, socio-cultural, or spiritual reasons, or simply by persuasion – and became the dominant religion.

               Mongol conquest of Persia and Mesopotamia

The Mongol invasion of Persia and Mesopotamia resulted in millions of deaths and ruined many cities. The early Mongol invaders were members of many faiths, so their persecution was not targeted against Zoroastrians.

However, within half a century of the conquest, the leader of the Ilkhanate, Ghazan Khan, who had been raised a member of the Church of the East,  converted to Islam.

The subsequent conversions of members of the Ilkhanate to Islam had a detrimental effect on Zoroastrianism.

By the time the Mongols were expelled, Fars province had escaped major damage and Zoroastrians had moved to the north of Pars, primarily to the regions of Yazd and Kerman, where even today the main Zoroastrian communities are found.

ABC Flash Point News 2025.