The film dives angrily into the fray. It uncovers the classified church documents and the largely concealed money trail of Mormon contributions that paid for a high-powered campaign to pass Proposition 8. The Mormon involvement, the film persuasively argues, tilted the vote toward passage, by 52 percent to 48 percent, in its final weeks.

That involvement was concealed under the facade of a coalition with Roman Catholics and evangelical Christians called the National Organization for Marriage. Mormons raised an estimated $22 million for the cause. In the final week of the campaign, the film says, $3 million came from Utah. The money financed a sophisticated media barrage that involved blogs, Twitter and YouTube videos, as well as scary (and, according to the movie, misleading) television ads, and an aggressive door-to-door campaign whose foot soldiers were instructed on how not to appear Mormon.

The film personalizes the issue with interviews with Tyler Barrick and Spencer Jones, a gay couple from Mormon backgrounds, who married in San Francisco in June 2008 and were devastated to find their marriage legally delegitimized.

The documentary is really two films roughly stitched together. The first two-thirds tells the history of Proposition 8; the final third is a wrenching exploration of the effects on gay Mormons of the church’s strict taboo on homosexuality. We meet gay teenagers who were exiled from their families and are told about a rash of suicides at Brigham Young University. The reason Utah’s suicide rate is the highest of any state, the movie suggests, is the Mormon church’s absolute rejection of homosexuality, which one church elder calls “contrary to God’s plan.” Chris Buttars, a proudly homophobic Utah state senator, compared male coupling to bestiality. The movie shows the depth of religion-based loathing of homosexuality, like that of abortion, to be primal.

In the meantime the struggle to repeal Proposition 8 is under way.

8

The Mormon Proposition

Opens on Friday in Atlanta; Boston; Chicago; Dallas; Fort Lauderdale, Fla.; Honolulu; Houston; New York; Los Angeles; Phoenix; Salt Lake City; San Diego and Washington.