For most of his childhood in pre-revolutionary Iran, Dr. Ali M. heard virtually nothing about his family’s religious heritage. (He declined to share his full name out of concern for family members still living in the country) But when Ayatollah Ruhollah Khomeini seized power following the 1979 revolution that overthrew the Shah, Ali’s family left for Germany. Experiencing a foreign culture for the first time, Ali, who now works as a physician in southern California, began to ask questions about his background. “When I lived in Germany, I was going through my teenage years,” he explained. “I tried to find out who I am and what was going on around me in a world of chaos and displacement.”

Ask someone about the Zoroastrian religion and—assuming they’ve heard of it—you will typically get three responses. Your interlocutor might inaccurately describe followers of the Zoroastrian faith as “fire-worshippers.” He or she may recognize Zoroaster, the priest who founded the religion, as the protagonist of the German philosopher Friedrich Nietzsche’s classic work, “Thus Spoke Zarathustra.” And there’s the oft-quoted “fun fact” that Freddie Mercury, the flamboyant vocalist of rock group Queen, was and still is the world’s most famous Zoroastrian.

Much less well-known is that Zoroastrianism is a living faith, with communities in India, Europe, the United States, and the Middle East—especially Iran. Ten years ago, a study by the Federation of Zoroastrian Associations of America concluded that there were, at most, 190,000 followers of the faith around the world. But as Laurie Goodstein noted in The New York Times, there was reason to be skeptical of this number, because of the “wildly diverging counts in Iran, once known as Persia – the incubator of the faith.”

In common with other religions, Zoroastrians in Iran have confronted both persecution and a concerted attempt by the Islamist regime in Tehran to destroy the very foundations of their faith. One critical consequence of this—no doubt unintended by the ruling mullahs—is that growing numbers of Iranians inside and outside the country are exploring a faith that crystallized two millennia before the Prophet Muhammed appeared on the scene. “Converting back” to Zoroastrianism, as many refer to the process of rediscovering their roots, has encouraged a view of Islam as an alien Arab faith that was imposed on unwilling Persians during the Muslim conquest of the seventh century.

Ali began asking his parents about their religious heritage and ancient roots. That’s when he found out through conversations with his mother that his grandfather’s family was descended from the Zoroastrian priestly lineage

Anxious to acquire more knowledge about his hidden faith, Ali began studying Zoroastrian teachings. He learned about the three principles propagated by Zoroaster: Humata, Hukhta, and Hvarshta, “Good Thoughts, Good Words, and Good Deeds” in Avestan, an ancient Iranian language. He learned that fire, which plays such a central role in Zoroastrian religious ceremonies, represents the divine light of wisdom. Then he decided to undergo the Navjote, an initiation ceremony into the faith that is similar to a Bar Mitzvah.

At first, the priests whom Ali met in America were apprehensive about performing the ceremony, pointing out that doing so would be regarded as apostasy by Iran’s rulers, which could cost Ali his life if he returned home. According to Iran’s official records, Ali’s father is registered as a Muslim. Under Iranian law, children automatically take their father’s religion. Iranians who depart Islam for another faith face imprisonment or even execution.