A fresh new voice in nonfiction filmmaking, Ahsen Nadeem never intended to make the doc that became “Crows Are White” as deeply, disarmingly personal as it turned out, but in re-centering the focus on himself, he arrived at a much more honest movie. Approaching the subject in the vulnerable, open-book tradition of cine-essayists Ross McElwee (“Sherman’s March”) or Caveh Zahedi (“I Am a Sex Addict”), Nadeem, who was raised Muslim in Saudi Arabia, works through why he found himself so conflicted about his religious upbringing, as well as how to break the news to his parents that he intended to marry a non-Muslim woman. The result is an introspective — and at times uncomfortably irreverent — journey for both him and the audience.

Nadeem’s original intention was to investigate the “marathon monks” of Mount Hiei, Japan, who seek spiritual enlightenment by walking a repetitive course known as the kaihōgyō, equivalent to the circumference of the Earth (roughly 24,000 miles), over seven years. Tendai Buddhist monks are sworn to silence during this time, and must agree to either hang or disembowel themselves if they should fail. It’s safe to say, they take their faith seriously. Nadeem does not.

“I’m a fantastic liar,” admits director, whose family eventually relocated to Ireland, where he drifted away from Islam, while still feigning devotion for his parents’ benefit. Much of what follows reflects Nadeem’s true (non)belief: Disingenuous at best, if not downright disrespectful, the film serves as an avowed nonbeliever’s blithe assessment of centuries-old traditions that, to outsider eyes, can’t help seeming a little ridiculous. But then, if approached with skepticism, there’s an element of absurdity to nearly all religious practices, from circumcision (genital mutilation) to Communion (symbolic cannibalism) to the berserk hot-pink call-to-prayer clock that went off at random times in Nadeem’s childhood home.

After dedicating two years to convincing the monks to let him visit Mount Hiei and film their intensely private rituals, Nadeem blows it by forgetting to silence his cellphone during a meditation ceremony. He’s immediately ejected from the monastery and obliged to rethink the entire project. The documentary might have ended there, but instead, Nadeem keeps filming over several more years, during which he remains stubbornly committed to interviewing Kamahori, the monk he’d initially wanted to make the film about.

Strangely, Nadeem doesn’t seem to have prepared specific questions for this meeting, and when the long-pursued on-camera conversation does come (having completed the kaihōgyō, Kamahori is now free to talk), their session is interrupted by a phone call. This time, it’s the monastery phone that rings, cutting short the scene — perfect karma.

Maybe it’s the influence of Bill Maher (“Religulous”) and Albert Brooks (“Looking for Comedy in the Muslim World”), or else an extension of “The Daily Show” correspondents’ gotcha shtick, but when comedic filmmakers incorporate themselves in their work, they tend to make themselves look superior to their subjects. Not Nadeem. He’s candid about his spiritual uncertainty and personal shortcomings. For years, the director admits, he has been leading a double life: He lies to his parents, allowing them to believe he still prays regularly, while neglecting to tell them about his fiancée, Dawn.

He and Dawn practice far more healthy communication than Nadeem does with his mom and dad, and she’s surprisingly open on camera (a scene of her nervously pacing toward the end cinches the film’s emotional journey). At one point, Nadeem films his wife-to-be wondering, “If he doesn’t know who he is, how can I fully invest in a future with this person?” — a fair question. Although the movie inevitably builds to the moment when Nadeem must “come out” to his parents, it’s not clear how much he actually tells them. (Do they know that he’s made a near-complete break from his faith?)

Back in Japan, while trying to salvage the film he was making about Kamahori, Nadeem meets Mount Hiei’s lowest-ranking monk, Ryushin, who speaks English and helps to demystify certain Tendai customs — like the one where monks are locked in complete darkness and not allowed to lie down or sleep for 90 days. Ryushin is on a spiritual journey of his own, trying to reconcile his love for sweets and heavy-metal music with the asceticism of his peers. It’s amusing but also quite humanizing to witness a monk wearing headphones or attending a Slayer concert. Ryushin’s attitude aligns more with the Western pursuit of personal gratification than with the relatively self-effacing position of the senior monk who explains the film’s title: Religion relies on faith — i.e., trusting what one’s spiritual leaders say, even when it appears to be illogical, difficult or false.

Remember, Nadeem opens “Crows Are White” by confessing his own habit of dishonesty. Throughout, the filmmaker presents himself as lazy and undisciplined, awestruck by the monks. But think about what this film represents: years of borderline-obsessive dedication to chronicling a closed religious community, plus the commitment and humility to return after making a fool of himself early on. For some, walking 24,000 miles in wordless silence is the route to enlightenment. For Nadeem, he paved his own path.