A few years ago, a friend sent me an e-mail with the subject line “Reza Aslan is insulting you!” The message was an excerpt from an interview with Aslan, by then already a well-known commentator on religion, in which he was asked about the role that scholars should play in informing public debates about the Islamic world. “You can’t be trained to speak to the media in a weekend seminar before going on Anderson Cooper,” he said. “I honestly think that the best hope that we have is to foster a new kind of student, one who doesn’t spend eight years in the basement of Widener Library at Harvard poring over a thirteenth-century manuscript and writing a dissertation on the changes in the vowel markings of a sentence.” At the time, I was in the basement of Widener, examining half a dozen manuscripts and writing a dissertation on a fourteenth-century Arabic encyclopedia. The caricature stung, but I feared he was right. Less than a decade after 9/11, there was even more public hostility toward Islam than there is today; few scholars of religion had mastered the rhetorical tools to thrive in the arena of public debate.

Aslan, however, moved with facility among conservative Christians and liberal atheists, scattering data points and sound bites as he emerged as one of the most prominent Muslim-Americans in mainstream media. Now a best-selling author and producer, Aslan has become known for the elegant smoothness with which he toggles between the postures of spokesperson for his own faith and detached scholar of other traditions. During a 2013 interview, a Fox News anchor asked him how a Muslim could write a book about Christianity. The clip of Aslan’s response went viral: “I am a scholar of religions with four degrees—including one in the New Testament—and fluency in Biblical Greek, who has been studying the origins of Christianity for two decades,” he said. “I’m not sure what my faith happens to do with my twenty years of academic study of the New Testament.” In a recent interview in the Times, Aslan described his family as a model of convivencia, a happy gaggle in which a Christian mother, Muslim father, and two sons (“one of whom is convinced he’s Jewish, and one of whom, after he read the Ramayana, was, like, ‘That’s it, I’m Hindu’ ”) live together under a single roof. A similar liberality is at play in Aslan’s new CNN miniseries, “Believer,” whose finale aired on Sunday night. (Tagline: “I’ve been studying the world’s religions for twenty years. Now I’m going to live them.”)

The show is a kind of spiritual “Parts Unknown,” in which religions are ingested like sea-urchin roe—but without Anthony Bourdain’s lovable loutishness. In six episodes, Aslan spends time with human-flesh-eating sadhus in Varanasi, an ark-building Hawaiian apocalyptic cult, goat-sacrificing Haitian vodouistes, excommunicated Scientologists, devotees of Santa Muerte in Mexico City, and ultra-Orthodox Jews in Israel. The first episode examines the Aghori sect of Hinduism, some of whose adherents deploy spectacular practices, like eating human remains and lying on corpses, in order to combat traditional Hindu notions of purity and pollution. In one scene, Aslan is chased by an Aghori nomad who, after feeding him a piece of human brain, tries to urinate on him. The episode’s dénouement, in which Aslan tours a modern Aghori orphanage, elementary school, and leper clinic, and finds, as he puts it, “the Hinduism I was looking for,” did little to assuage Hindu activists protesting outside CNN offices, who felt that the show was sensationalist and short on substance.

After watching the first couple of episodes, I was inclined to agree. Each begins in the realm of benightedness—doomsday prophets rolling around on the floor; gurus eating honey out of skulls—and moves toward enlightenment. By the end of the hour, Aslan has laid bare what is beautiful about the religion and what it offers to its adherents. The answer is the same for Hindus and ark-builders. “Religion isn’t about scripture or temples or priests or rules or regulations,” Aslan says, standing in a circle at twilight with the followers of JeZus, the prophet of the Rainbow Village doomsday cult. “It’s about the individual, and the quest for meaning, the idea that there is something more to life than just what we see with our eyes, what we feel with our hands.” It’s an attractively cosmopolitan, à-la-carte approach to faith, and yet merely stating that scriptures, temples, priests, and rules are insignificant does not make it true for countless believers. As a scholar of religion, Aslan surely knows this, which is why “Believer” amounts to a canny sort of evangelism—not for any one religion in particular, but for Aslan’s own brand of universal spirituality, which regards religions as nothing more than different languages for expressing the same meanings.

As the series goes on, Aslan does find ways to confront the fuller bandwidth of religion’s role in society. In Episode 5, he listens to transgender prostitutes and prisoners confess what spiritual resources they find in Santa Muerte, a Mexican folk saint that the Catholic Church has denounced as the center of a death cult. “It’s a new community, a new religion really, that’s forming before our eyes,” he marvels after a street festival held in honor of the saint. “It’s amazing to me.” Aslan is drawn to the acquisitiveness of contemporary religious experience—the way that religions are constantly changing, innovating, shedding old rites and symbols and acquiring new ones; in a way, the idea underwrites the conceit of “Believer,” in which the same person takes on the habit of a different faith every week.

The season finale goes further still, offering the viewer a glimpse of the series that “Believer” could have been—one that wrestles with the agonistic dimensions of religious identity instead of trying to assimilate them into a beatific meta-faith. In it, Aslan examines a group of ultra-Orthodox Israeli Jews known as the Haredim, whose numbers and influence have in recent years grown dramatically, triggering a debate in Israeli society about the relation of religion to democratic politics. As the Rabbi Yaakov Litzman, Israel’s Minister of Health and a member of the Haredi community, tells Aslan, “The land of Israel is because of the Torah. . . . The Torah has never changed, and we will never change.” The changes the Haredim have opposed include demands by women’s groups to dismantle gender-segregation protocols at the Wailing Wall, and civil rights for same-sex couples. Aslan is disturbed by the intransigence of the Haredim, whose political ascendance he likens to the Islamic Revolution, which led his family to flee Iran, in 1979, and the secular Jews he speaks to evince a similar frustration. This change in tone threatens to undermine the cheeky ecumenism of Aslan’s larger method. Why do renegade Scientologists get the benefit of the doubt, while ultra-Orthodox Jews do not? Perhaps there is a limit to universalist tolerance, after all.

Tellingly, Aslan’s foil to the Haredim is not the group of secular Israelis who invite him over for Shabbat dinner to rail against the menace of orthodoxy, raising a toast to “the secular Messiah.” Instead, he stumbles upon a subsect of Haredim, an exuberant band of Hasidic Jews called the Na Nachs, who preach a religion of happiness through trance music, reggae, and ecstatic dance. Like other Haredim, the Na Nachs hold orthodox theological views on gender roles, and they are exempt from military service. Wives work so that their husbands can devote their days to prayer, study, and proselytizing. But the Na Nachs’ unique belief that “happiness is basic, the beginning of everything,” suggests to Aslan that they may represent a bridge between secular and religious Jews. In their jubilant street performances, he finds deliverance from the strictures of Rabbi Litzman: “No Wall, no Torah, no yeshiva, no separation, no dos and don’ts. Just pure, unadulterated happiness.” He also finds the grand finale his series needs, as he and the Na Nachs dance together in a cemetery near Jerusalem. When one of them asks Aslan if he is Jewish, Aslan surprises him by saying no, then looks at the camera and shrugs. “I feel Jewish today,” he says.