Religion rarely receives any time in prime time. So four hours devoted to Mormonism is going to stand out on the TV landscape.

PBS' "The Mormons" deserves the attention because the documentary takes a thoughtful, probing look at a religion that has angered and mystified millions through U.S. history. History matters as much as religious doctrine in this epic American story of outsiders becoming insiders.

The program premieres as Mormons gain new stature: Harry Reid leads Senate Democrats, and Republican Mitt Romney runs for president. Director Helen Whitney didn't interview either in the program, which airs next week. But Whitney has found first-rate speakers and assembled the material with style. She achieves balance by interviewing believers and skeptics, church insiders and the excommunicated. Most crucially, she provides respect that has often been denied the religion.

Utah historian Ken Verdoia points to presidential inaugurations to trace the Mormons' rise. In the span of a century, presidents went from decrying the religion to asking the Mormon Tabernacle Choir to sing.

Mormons "were considered a knife at the back of the American experience," Verdoia says. "Now they are, in fact, considered in some ways the very embodiment of what it means to be American. How was that brought about?"

The first half examines the religion's history. Joseph Smith's vision of the angel Moroni led to publication of the Book of Mormon and the church's founding in 1830.

"It was religion made in the USA," author Simon Worrall says. "For the first time, you had a home-grown religion, a home-grown prophet."

And it was a source of controversy immediately, with newspapers and traditional Christians decrying what they saw as blasphemy and fraud. The Mormons faced persecution in Ohio, Missouri and Illinois. Smith's death at the hands of an Illinois mob could have been the end.

But Brigham Young emerged as leader and guided believers to the Valley of the Great Salt Lake in 1847. Whitney recounts that heroic feat in stirring style.

She also explores dark chapters in Mormon history. In 1857, Mormons attacked a wagon train in what became known as the Mountain Meadows Massacre. At least 120 travelers were slain, and a church cover-up began.

"How did these decent, religious men who had sacrificed so much for what they believed in, how did they become mass murderers?" historian Will Bagley asks.

Whitney turns to polygamy without sensationalism. Church leader Young would marry more than 50 women. The program estimates that just 20 percent to 30 percent of Mormons practiced polygamy.

Still, plural marriage would hurt the Mormons' image and stall Utah statehood for nearly 50 years. In 1890, the church renounced polygamy.

The documentary's second half explores the church's growth, mission and determination to control its message.

Speakers cite family as central to Mormonism's growth and endurance. ("South Park" made the same point in an episode on Mormonism.)

"It's the Mormon fixation on the family as a coherent unit that's so important, says Jon Butler, a Yale professor of religion. "Within Mormonism there is an emphasis on the collective, the collective sense of the family."

The most moving segment focuses on a family sustained by faith as a 23-year-old daughter deals with a fatal condition. But Whitney also explores why the religion isn't accommodating to intellectuals, feminists, gays and dissenters.

Trevor Southey, an excommunicated gay, says, "There's something terribly tragic that not only Mormonism but most religions have such a hard time with the odd ducks."

For a lot of their history, the Mormons were odd ducks. Savvy public relations helped change that situation.

"One of the major PR tools of the church has been the tabernacle choir," says U.S. Sen. Robert Bennett, R-Utah. "When they got on radio, they became the nation's choir. The tabernacle choir has been an extraordinary ambassador for the church."

To its great credit, "The Mormons" goes beyond public relations to ask important questions in an intelligent way.