Zoroastrianism or Mazdayasna is one of the world’s oldest continuously practiced religions, based on the teachings of the Iranian-speaking prophet Zoroaster (also known as Zaraθuštra in Avestan or Zarthost in Modern Persian). Zoroastrianism has a dualistic cosmology of good and evil and an eschatology, predicting the ultimate conquest of evil by good. Zoroastrianism exalts an uncreated and benevolent deity of wisdom, Ahura Mazda (Wise Lord), as its supreme being. The unique historical features of Zoroastrianism, such as its monotheism, messianism, judgment after death, heaven and hell, and free will may have influenced other religious and philosophical systems, including Second Temple Judaism, Gnosticism, Greek philosophy, Christianity, Islam, the Baháʼí Faith, and Buddhism.

With possible roots dating back to the Second Millennium BCE, Zoroastrianism enters written history in the 5th century BCE. It served as the state religion of the ancient Iranian empires for more than a millennium, from around 600 BCE to 650 CE, but declined from the 7th century CE onwards following the Muslim conquest of Persia of 633–654 and subsequent persecution of the Zoroastrian people.  Recent estimates place the current number of Zoroastrians at around 110,000–120,000 at most, with the majority living in India, Iran, and North America; their number has been thought to be declining.

 Prior to Zarathustra, the ancient Persians worshipped the deities of the old Irano-Aryan religion, a counterpart to the Indo-Aryan religion that would come to be known as Hinduism. Zarathustra, however, condemned this practice, and preached that God alone – Ahura Mazda, the Lord of Wisdom – should be worshipped. In doing so, he not only contributed to the great divide between the Iranian and Indian Aryans, but arguably introduced to mankind its first monotheistic faith.

The idea of a single god was not the only essentially Zoroastrian tenet to find its way into other major faiths, most notably the ‘big three’: Judaism, Christianity and Islam. The concepts of Heaven and Hell, Judgment Day and the final revelation of the world, and angels and demons all originated in the teachings of Zarathustra, as well as the later canon of Zoroastrian literature they inspired. Even the idea of Satan is a fundamentally Zoroastrian one; in fact, the entire faith of Zoroastrianism is predicated on the struggle between God and the forces of goodness and light (represented by the Holy Spirit, Spenta Manyu) and Ahriman, who presides over the forces of darkness and evil. While man has to choose to which side he belongs, the religion teaches that ultimately, God will prevail, and even those condemned to hellfire will enjoy the blessings of Paradise (an Old Persian word).

How did Zoroastrian ideas find their way into the Abrahamic faiths and elsewhere? According to scholars, many of these concepts were introduced to the Jews of Babylon upon being liberated by the Persian emperor Cyrus the Great. They trickled into mainstream Jewish thought, and figures like Beelzebub emerged. And after Persia’s conquests of Greek lands during the heyday of the Achaemenid Empire, Greek philosophy took a different course. The Greeks had previously believed humans had little agency, and that their fates were at the mercy of their many gods, who often acted according to whim and fancy. After their acquaintance with Iranian religion and philosophy, however, they began to feel more as if they were the masters of their destinies, and that their decisions were in their own hands.

Though it was once the state religion of Iran and widely practised in other regions inhabited by Persian peoples (eg Afghanistan, Tajikistan and much of Central Asia), Zoroastrianism is today a minority religion in Iran, and boasts few adherents worldwide. The religion’s cultural legacy, however, is another matter. Many Zoroastrian traditions continue to underpin and distinguish Iranian culture, and outside the country, it has also had a noted impact, particularly in Western Europe.

Centuries before Dante’s Divine Comedy, the Book of Arda Viraf described in vivid detail a journey to Heaven and Hell. Could Dante have possibly heard about the cosmic Zoroastrian traveller’s report, which assumed its final form around the 10th Century AD? The similarity of the two works is uncanny, but one can only offer hypotheses.

It wasn’t only in Western art and literature that Zoroastrianism made its mark; indeed, the ancient faith also made a number of musical appearances on the European stage. 

In addition to the priestly character Sarastro, the libretto of Mozart’s The Magic Flute is laden with Zoroastrian themes, such as light versus darkness, trials by fire and water, and the pursuit of wisdom and goodness above all else. And the late Farrokh Bulsara – aka Freddie Mercury – was intensely proud of his Persian Zoroastrian heritage.

For all its contributions to Western thought, religion and culture, relatively little is known about the world’s first monotheistic faith and its Iranian founder. In the mainstream, and to many US and European politicians, Iran is assumed to be the polar opposite of everything the free world stands for and champions.