(CNN) - Deeply personal and equally moving, "Believer" documents Imagine Dragons lead singer Dan Reynolds' crusading campaign on behalf of LGBTQ rights, in direct conflict with the teachings of the Mormon Church under which he was raised.
As Reynolds notes, the terms "Mormon" and "rock star" don't exactly go hand in hand, but the singer's commitment to his religion sounds sincere. He speaks at some length about his upbringing, and his initial reluctance to marry his wife, Aja Volkman, because she wasn't Mormon, which meant departing from the marry-within-the-faith path followed by his brothers.
Still, it's Reynolds' awakening regarding the church's hostility to gay marriage, and promotion of "solutions" like "mixed-orientation marriages" (prodding gay and lesbian members to wed straight people of the opposite gender) and celibacy, which prompts him to stay and fight rather than simply leave.
"Believer" (a name that doubles as the title of one of the group's hits) zeroes in on the toll of those policies, starting with an alarmingly high suicide rate among gay teens in the church's home state of Utah. Those testimonials -- in some instances from grieving parents -- are devastating.
Filming in 2017, Reynolds -- shown tooling around mixing the band's hit "Thunder" -- decides, naturally, to put on a show: an awareness-raising concert called the LoveLoud Festival. Director Don Argott chronicles every step in the planning and build-up to that event, but the waterworks really open during the show itself, from seeing parents embrace their children to LGBTQ adults talking about what a difference such an event would have made when they were young and feeling isolated.
The documentary -- which in addition to the rock songs boasts a musical score from movie composer Hans Zimmer -- also features Tyler Glenn, the lead singer of Neon Trees, who has his own issues with the church, being gay and Mormon.
"Believer" will likely be written off as propaganda by opponents of the gay-rights movement, but Reynolds seems determined to soldier on, in a manner -- informed by his experience in the church -- designed to persuade rather than judge. That's clear from the beginning, during a radio interview in which Reynolds discusses what he feels to be his obligation to speak out against things -- including the church's teachings regarding homosexuality -- that are hurting people.
On that score, and others, "Believer" and its headliner hit all the right notes, in a film that delivers another kind of thunder.
"Believer" premieres June 25 at 8 p.m. on HBO.
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