When Parsi Zoroastrians, having fled Persian persecution, arrived on Indian soil sometime between the 8th and 10th centuries, the story goes, an Indian ruler sent a cup full of milk. The intention, clearly, was to convey that India was filled to the brim. The Zoroastrian king inserted either sugar—or in some tellings, a ring—and sent the cup back to suggest that not only was there room for his people, but they would also enrich Indian society if permitted to settle.

Certain restrictions curbed the private and communal lives of the Zoroastrian asylum seekers, but they were largely allowed to thrive in India. Roughly a dozen centuries later, many Parsis have settled in the diaspora, where they’re encountering a different challenge: assimilation and a not-too-distant scenario in which, some worry, there will be no Zoroastrians left in the world. Sugar has a tendency to dissolve in milk.

This worry is often directed toward young Zoroastrians, whose minds—and perhaps more importantly, hearts—may determine the future of the religion. Decisions about dating and marriage can also be decisions about whether to stay within their community: Zoroastrianism is a patriarchal tradition, so the children of Zoroastrian women who marry outside the faith are not accepted, and even shunned, in many communities. Meanwhile, children of Zoroastrian men who intermarry are likelier to be accepted.

Unlike, say, Judaism, Christianity, and Islam, Zoroastrianism calls for individual rather than communal worship services in its houses of worship, called fire temples, and it prescribes “good thoughts, good words, good deeds” rather than the plethora of positive and negative rules that govern other religious traditions. Zoroastrianism does have holidays and rituals, and adherents go through an initiation rite, which some people compare to a bar or bat mitzvah, called “navjote.” Although it might appear to outsiders as though fire is worshipped in the temples, Zoroastrians say that fire is a symbol of the divine, due to its warmth and light, rather than the divinity itself. Parsis, the descendants of the Zoroastrians who fled Iran for India, represent the largest portion of the Zoroastrian population globally; the other portion lives in Iran.

Tracking demographics of the group in North America and worldwide isn’t easy. The religion, which adherents often refer to as the world’s first monotheistic tradition and which dates back to the 6th century B.C., is included in a category of “other world religions” in Pew Research Center reports, which also includes Sikhs, Baha’is, Taoists, Jains, Rastafarians, Confucians, and Druze. The lot, according to two 2015 surveys, account for just 0.3 percent of U.S. adults and 0.8 percent of the global population. The World Religion Database estimates there are 200,000 Zoroastrians worldwide, according to Pew; the Federation of Zoroastrian Associations of North America, or FEZANA, suggests that figure is too high. According to a study done by the organization’s journal in 2013, the world Zoroastrian population dropped from 124,953 in 2004 to 111,691 in 2012—a 10.6 percent decline. Although the North American Zoroastrian community actually grew during that period by 24.4 percent—numbering 20,847 in 2012—and by 33.5 percent in the United States, this population is relatively small compared to that of India, which saw a 12.4 percent decline from 69,601 in 2004 to 61,000 in 2012.

These figures, though, weren’t gathered as part of a formal demographic survey. “There’s no way really for us to compute how many Zoroastrians there are in the U.S. and in North America,” said Dinyar Patel, an assistant professor of history, including that of modern South Asia and Zoroastrianism, at the University of South Carolina. “Neither the U.S. nor the Canadian census does enumeration by religion.”

Patel, 34, who grew up in a Bakersfield, California, community with two other Parsi families, prioritized marrying within the faith, even though his parents didn’t pressure him to do so. “From the very beginning when I was starting to look out, I only looked within the community,” he said. “There are so many small things that make a big difference: celebrating the same holidays and traditions, going to the fire temple together, sharing the same idiosyncratic Parsi sense of humor, and of course having similar favorite foods,” he said.

He and his wife, who have been married for two years, are in a long distance U.S.-India marriage and do not have children yet. But when they do, Patel feels strongly committed to passing down his religion. “The only way this community will survive is through the personal decisions of each individual Zoroastrian,” he said. “While change is inevitable and the community needs to a bit more pragmatic on the issue of intermarriage, I still strongly believe that marrying within the community is the best possible safeguard for ensuring that we don’t get relegated to the history books in the next few generations.”

Patel’s wife, Parinaz, 27, agreed. “Even though we were from two different countries, we realized that we had a lot in common and that is, in large part, due to the fact that we share the same religious beliefs and values,” she said.

Dinyar and Parinaz, who grew up in India, met at a Zoroastrian community event in Dubai. “I really strongly think that if you make it a priority [to find a Zoroastrian spouse], and if you are sincere in it being a priority, you will find someone and make it work,” he said. He said he knows of middle-aged, intermarried Zoroastrians who still feel guilty that their kids aren’t connected to their religious heritage. “I find those experiences quite striking—that people who are 50 or 60, who have been married to their spouses for so long, still carry around such guilt,” he said.

For those who do want to date and marry within the religion, there aren’t necessarily many options. One approach is to visit a matchmaker: Roshan Rivetna, a Zoroastrian who lives in Illinois, keeps files on some 200 eligible Zoroastrians. Since she was profiled by the New York Times in 2009, “the situation has become worse,” she said, relying on the study by the FEZANA journal, where she used to be an editor; the rate of intermarriages, she estimates, has risen from 40 percent to 60 percent.

Zoroastrians pray together at the opening of Kamran Dar-e Mehr, a center run by the Zoroastrian Association of Metropolitan Washington in Maryland. (Mark Fitch)

Otherwise, it can be tough to find a Zoroastrian to be with. Patel said he has heard about a mobile dating app under development in India intended for Zoroastrians; he has seen no equivalent in the United States. It is, he said, “a pretty big failing.” There doesn’t seem to be much youth programming in the community, although an organization called Zoroastrian Return to Roots has taken about 45 Zoroastrians, aged 22 to 35, on 15-day trips to India. The program is designed to expose young people to their heritage, but not to make matches, said Arzan Sam Wadia, a New York-based architect who helps run the trips and serves on FEZANA’s board. “People have realized out of experience over the years that if you actually call it a dating event the turnout is not as much, because some young folks are taken aback,” he said. “They don’t want to be doing a speed-dating thing.” There are also events such as the World Zoroastrian Youth Congress and meet-and-greets across the country; setting people up may not be the goal, but it’s a hope. “The idea is you get young people of the faith together and maybe they fall in love with each other, find a partner, and get married,” he said. “It’s not done with the zeal or the focus of an actual dating service.”

Some young Zoroastrians may want to date within the religion and find the prospect daunting. But for others, intermarriage doesn’t seem so menacing. Cyrus Guzdar, 35, grew up Zoroastrian in Columbia, Maryland, and is currently dating a 30-year-old woman, Claire Markham, who grew up Catholic. The two met about a year ago online; Markham, a self-declared “religion nerd” who studied theology in college and graduate school, was fascinated by Guzdar’s religious background. “He’s definitely the first Zoroastrian I ever met,” she said. “There is something a little bit special about stumbling across someone who is one of maybe 200,000.”

Growing up, Guzdar never felt any pressure from his parents to marry within his religion. He and his mother attend an annual memorial service at the Zoroastrian Association of Metropolitan Washington in honor of his father, who passed away several years ago, and he said he sometimes tags along to events with his mom, who has felt the desire to be more engaged in the community of late. At the temple, he has found that most of the couples are interfaith. “With the older generation, like my parents’ age, the couples are all Zoroastrian for the most part,” he said. For some Zoroastrian parents of this generation, it may be “a little bit more of a feather in their cap” when their children marry within the fold, but he said that’s not his mom’s attitude. “I don’t think she’d like Claire more if she was Zoroastrian,” he said.

The exterior of the Kamran Dar-e Mehr Zoroastrian center (Mark Fitch)

Guzdar believes it’s important for children to know their ancestry; plus, he said, Zoroastrianism has a lot to be proud of in its history, including a focus on education and women’s equality. For her part, Markham anticipates raising children with exposure to both Zoroastrianism and Catholicism—“sometimes going to church, and sometimes to fire temple,” she said. In her view, religious life doesn’t have to involve a choice between appreciating the beauty of one’s tradition and recognizing the beautiful aspects of other faiths.

Guzdar and Markham have an advantage though: He’s the Zoroastrian in the relationship, not her. In some communities, “a woman marrying outside the faith has limited or no access to the community’s resources and religious institutions,” said Dilnavaz Bamboat, 37, who currently lives in Silicon Valley. Bamboat, a former therapist and early childhood educator, is now a freelance writer and blogger and a full-time mother. “Her children are not considered Zoroastrian, whereas this does not apply to men.”

In Bombay, where she grew up, Bamboat’s choice to marry a non-Zoroastrian led to conflicts with her family and the community. “It was one—but certainly not the only—reason we moved to America: to be free of prejudiced social circles and raise our child in his mother’s culture and religion if we so wish,” she said. In conservative circles in Bombay, including part of her family, interreligious marriages, such as her own, were not looked upon favorably, she said. "Women marrying out are frequently excommunicated."

They had heard things were different in the U.S., but they weren't sure how they would be treated. They went to an event, and knew nobody but her aunt and uncle who lived in the area. "There we met a bunch of folks our age, who encouraged us to come to the community's annual summer picnic, and then there was no looking back." Their fellow Zarthoshti Anjuman of Northern California (ZANC) members have been "so friendly and welcoming of us as a couple," she said, and her spouse fits right in and even volunteers. "We have friends who meet even outside of ZANC events, which is funny, because I barely had any Parsi friends in Bombay!"

ZANC has a number of intermarried couples, and no one treats them any differently, she said. "They are welcome to every single event we have, religious or cultural. Our priest is open minded and a great resource for us," she sad. "Our ZANC president is married to a white, German man, and he is our treasurer, and nobody bats an eyelid. You definitely wouldn't see that happening in Bombay where the hostility and discomfort are apparent. Little wonder then, that our numbers are growing in North America as the community thrives, while they are in decline all over India."

Not all North American communities are the same, though. Lylah Alphonse, an editor at U.S. News & World Report based in Boston, has also been critical of how intermarried women tend to be treated. “Without accepting the children of intermarriage and allowing conversion, we will indeed preserve our culture—as a chapter in the history books, not as a thriving and progressive community,” she wrote in 2009. From a demographic perspective, she said in an interview, the expectation that Zoroastrians will only marry others of their religion has been destructive. “If you’re not allowed to marry outside the community—[or] if you do, you’re no longer counted and your children aren’t counted—it only makes sense that the numbers are continuing to fall rapidly,” she said.

Alphonse’s Parsi mother grew up in India, while her Roman Catholic father was raised in Haiti. Her grandmother, Roda Mistry, was the first Zoroastrian member of India’s parliament, and the country’s minister for women’s welfare and tourism. In 1979, she insisted that Alphonse should be allowed to have her navjote in Hyderabad, and that both of her brothers should have theirs in a joint 1983 ceremony in New Delhi. “When she decided to break the rules, it was a pretty significant event,” Alphonse said. Her own writing on Zoroastrianism has prompted critical letters, including one from a priest in Mumbai who said the world would have been better had she not been born. Alphonse is married to a non-Zoroastrian and is not raising her children Zoroastrian, she said.

This disdain for women who intermarry—and, perhaps, those who vocally push back against the cultural standards of the community—is part of a larger pattern of how women have, at times, been treated in the religion, said Patel, the professor at the University of South Carolina. Although Zoroastrianism teaches that women are equal to men in terms of things like property holding, “like every other religion, [it] has a long history of oppressing women,” he said. For example: “Women were not allowed to be in the same house as men during their periods,” he said. In terms of intermarriage, he said, there’s no scriptural basis for treating men and women who intermarry any differently. “I’ve heard this stuff for the past 10 to 15 years so often,” he said. “‘We are liberal.’ Or ‘The women in the community are so advanced, but the men are so unadvanced.’ The more you study them, the more you realize a lot of it is completely untrue.”

The pressures around dating and marriage in Zoroastrianism have certain parallels to those in Judaism, another small religion with a rich history: a taboo against intermarriage, a system of inherited religious identity, a relatively small dating pool. But as Patel noted, unlike Jews, Zoroastrians don’t have anything in their history like the Holocaust, which shaped a sense of Jewish identity and obligation among the children and grandchildren of survivors. Even if many Zoroastrians feel the pressure that comes along with being a member of an increasingly dwindling religious community, they don’t necessarily act on that pressure, according to Patel. “I think it’s at the back of everyone’s minds,” he said.

This is perhaps the central question for Zoroastrianism, Judaism, and other small religions: What does it mean for a religious tradition, with a longstanding and proud past, to teeter on the brink of oblivion and quarantine to history books? This is not just a matter of numbers; it’s also a question of how elastic and accommodating to modern times a religion can be without losing its central identity. As Tevye famously said in Fiddler on the Roof, “If I bend that far, I’ll break.” Of course, the Jewish peasant did bend, acknowledging his intermarried daughter, and one could argue that he didn’t break.

It’s not clear, however, that Zoroastrianism would necessarily thrive and increase exponentially if it became more progressive and more amenable to contemporary sensibilities. A more welcoming fold isn’t always able to bring estranged members back in, and what seems hospitable and tolerant to some may strike others as a departure from the core tenets of their religion. Crises are part of lifecycle of small religions—as are, sometimes, endings.

“If you talk to any Parsi, whether in North America or in India, they will easily be able to identify several family members who never got married,” said Patel. “Obviously you won’t get to a point in say, 100 years, where there are no Parsis. It’s not a linear drop.” But the existential threat to the community is real, he said. “The community is kind of still asleep at the wheel.”