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Mitt Romney's speech to the Republican National Convention on Thursday will be his chance to tell his story to the world. Perhaps the most unique part of that story is his devout Mormon faith.

Romney comes from a prominent Mormon family. He's held important leadership positions in the Church of Jesus Christ of Latter-day Saints. But he rarely talks about his faith. When he does, he seems uncomfortable.

In a recent interview on the Catholic television network EWTN, and in another in Cathedral Age magazine, Romney discussed his faith in broad terms. He never used the word "Mormon."

But Joanna Brooks, a professor at San Diego State University and a Mormon herself, is encouraged that at the very least, he's beginning to open up.

"I think one of the unintended consequences of his reticence was he gave off the sense that there's something to be ashamed of in Mormonism, something to be feared," Brooks says.

Brooks, who's the author of The Book of Mormon Girl, says Romney should talk about his days as a missionary, and the millions of dollars he's given to charity. He should play up the untold hours he spent as a lay pastor and regional president in Massachusetts, she says, when he prayed with people, counseled them and helped those who were struggling economically.

"These are powerful parts of Romney's faith story that might assist voters in seeing him as more than a wealthy, sort of evasive bureaucrat — seeing him as a caring human being."

But along with the benefits of talking about his faith, there are risks, says Robert Jones, who heads the polling firm Public Religion Research Institute.

"If he starts opening the door to the specifics of Mormon theology, questions about the Book of Mormon versus the Bible, then he's in very dangerous territory," Jones says.

That is particularly true with white evangelicals, a powerful part of the Republican base. Most evangelicals don't consider Mormons to be Christians because Mormons have an additional sacred text as important as the Bible. They have a different concept of the Trinity, and believe that everyone is saved. There are the historical controversies, and the church's history of polygamy and racism. And then, says Brooks, there are the doctrines that strike some non-Mormons as, well, weird.

"They hear, for example, that Mormons believe they can have their own planet, which is sort of a cartoon of a much richer doctrine. They hear about underwear that Mormons wear, and it all seems so goofy," she says.

Brooks says that these aren't a big part of Mormonism. While the theology does say people can become like gods and get their own planets, it's downplayed these days. As for the white cotton underwear that Mormons wear, it's just a reminder to live a holy life.

Pollster Jones notes that Romney faces another hurdle as he tries to explain his faith. Most Americans don't know any Mormons because they're concentrated in Utah and the Mountain West.

"And so, therefore, they rely on things they hear in the media. They rely on pop culture references such as the Broadway musical The Book of Mormon or South Park or Big Love," Brooks says.

Mark DeMoss, an evangelical and a senior adviser to Romney, says it doesn't matter. People will be voting for a president, not a national pastor.

"On a personal level and a spiritual level, I might care a great deal about what somebody believed doctrinally. In the context of a presidential election, I don't care," DeMoss says.

What evangelicals do care about is shared values.

"When it comes to the importance of family and the centrality of marriage, the responsibility to reward industry and to reward thrift and to reward the moral virtues, yes, there's a great deal in common," says Albert Mohler, president of Southern Baptist Theological Seminary in Louisville, Ky.

Pollsters says that while evangelicals have come to approve of him, Romney has struggled to excite them. To rally the evangelical troops — who overwhelmingly want a president with strong religious beliefs — Brooks says Romney needs to publicly embrace his Mormon faith, despite the stereotypes.

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