"Almost 50 years ago, another candidate from Massachusetts explained that he was an American running for president, not a Catholic running for president," Romney said. "I do not define my candidacy by my religion. A person should not be elected because of his faith nor rejected because of his faith."

But 2008 isn't 1960. Now candidates are expected to discuss their religious traditions. And The Church of Jesus Christ of Latter-day Saints, the official name Mormons give their faith, is much smaller, newer and more controversial than Catholicism.

A Pew Research Center poll conducted in August found that 25 percent of voters are less likely to vote for a Mormon candidate, and 31 percent said Mormons weren't Christians.

Such views could hurt Romney in Iowa, where he's led almost all year after investing millions in ads and organization. Still, former Arkansas Gov. Mike Huckabee, a Baptist minister, has overtaken Romney in recent polls.

Those expecting a theology lesson on Mormonism won't find it in Romney's remarks. He did embrace his religion, which teaches that Jesus Christ visited America after his resurrection and told a modern-day prophet, Joseph Smith, to restore his true church. "I believe in my Mormon faith and I endeavor to live by it," Romney said.

He said he believed that Jesus Christ was the "son of God and the Savior of mankind," but acknowledged differences with traditional Christian faiths.

"My church's beliefs about Christ may not all be the same as those of other faiths," he said. "Each religion has its own unique doctrines and history."

He made it clear that he'd stick by his faith and never "disavow one or another of its precepts. ... Some believe that such a confession of my faith will sink my candidacy. If they are right, so be it."

Romney got the most applause when he hailed the contribution of religion to public life and defended the right of Americans to put religion and its symbols in the public square. He noted that the Founding Fathers separated church and state but included references to God in many public symbols and ceremonies.

"We are a nation 'under God' and in God we do indeed trust," he said.

He said that his faith held common humanitarian values with others in America's religious heritage, including belief in human equality, the obligation to serve one another and a commitment to liberty. He said his marriage and family life showed that he lived by these values and that they'd inform his presidency.

John Green, senior fellow at the Pew Forum on Religion & Public Life, was impressed.

"He said, 'Look at my life and family,' and he offered a long list of other religions," Green said. "He showed how religion has played a positive role in politics."

The value of getting lofty like that, said Sen. Robert Bennett, R-Utah, a Romney backer, is that people will think of Romney not as a Mormon candidate but simply as a potential president.

"That's the key to this whole thing," Bennett said. "If we can get people to know Mitt as a person, any reluctance to vote for him because he's a Mormon would go away."