The two Republican presidential hopefuls wear their religion very differently, but both must face stubborn antagonism towards it

Four months before he succumbed to a lynch mob in 1844, Joseph Smith ordered the leaders of his fledgling church to "hunt out a good location, where we can build a city in a day, and have a government of our own, where the devil cannot dig us out". Smith never saw that place – he was gunned down in his prison cell – but his followers did after being driven out of America by persecution and making a 1,300-mile trail across the plains.

The bolthole they found was a basin almost wholly enclosed in the protective embrace of the Rocky mountains in what was still at that time Mexico. A century and a half later, the community they built there not quite in a day, Salt Lake City, stands as a monument to the refusal of those early believers to be cowed by American intolerance.

Today, Mormons, far from being outcasts, find themselves at the very core of America's cultural and political debate. On Broadway, The Book of Mormon has become the biggest musical hit in years.

In politics, from the Democratic Senate leader, Harry Reid, to Tea Party darling Glenn Beck, Mormons are front and centre stage. And, at the height of what is being called a "Mormon moment", two latter-day saints are in the race for the White House.

But it might be precipitous for the 2012 candidates, Mitt Romney and Jon Huntsman, to declare the old animosity towards Mormonism over. A poll last month found 22% of Americans unwilling to vote for a Mormon as presidential nominee of their party, a level of bias higher now than it was in the 1960s. By contrast, opposition to black, female, Catholic or Jewish presidents has steadily declined since the 1950s. The last time 22% of Americans said they would refuse to vote for a Catholic president was in 1959 (though they promptly confounded the pollsters and elected John F Kennedy).

Such stubborn antagonism is familiar to Romney, the putative frontrunner among the current field of Republican candidates for 2012, who arrives in London for a fundraising event.

When he last ran for the White House in 2008 he faced a barrage of accusations about his "false religion" and its approval of polygamy — a practice that the church ditched in 1890 to become a part of America with the creation of the state of Utah. So troubled was Romney by the outcry that he felt obliged to address the subject in a speech in which he promised that if he were elected he would "serve no one religion, no one group, no one cause".

"We were all surprised early in the 2008 campaign when we saw an outpouring of out-and-out prejudice," said Michael Otterson, the Mormon church's head of public affairs. "Naively we thought that people would look at us and see people of good values, but instead we heard all this nonsense about cults. It showed us we had a lot of work to do. We still do."

Romney and Huntsman have a lot of work to do too, judging from the polls.

At face value, the two men have much in common. They both come from rich, powerful Mormon families: Romney's father was governor of Michigan and Huntsman's invented the plastic boxes Big Macs are sold in. They share an ancestor, Parley Pratt, a contemporary of Joseph Smith's, making them distant cousins. They both served as Mormon missionaries. Romney went to France and Huntsman to Taiwan, where he learned the Mandarin that was a factor when President Obama appointed him ambassador to China.

But despite their similarities, the two men wear their faith utterly differently. Romney, 64, takes a traditional approach, professing his love of his faith and making the Mormon-dominated state of Utah the centre of his fundraising activities. In 2008 Utah contributed more than $5m to his campaign, far more per capita than anywhere else.

"Romney has the sense of the slightly older generation, and is constantly explaining what Mormonism is," said Matthew Burbank, a political science professor at the University of Utah. "Huntsman, on the other hand, says 'Yes, I'm a Mormon, but …'"

Huntsman has a very large family, which in itself is typical of a Mormon, but has made a point of introducing diversity into the upbringing of his seven children. One daughter was married in an Episcopalian church, and another, adopted from India, is being raised in the Hindu tradition.

In a recent Time interview, Huntsman said: "I'm a very spiritual person and proud of my Mormon roots," which to many Mormons came across as a less than ringing endorsement of the faith.

Huntsman's ambivalence might reflect his younger age – he is 51 – or it could point to a conscious strategy to avoid the issue. But should his White House bid become serious, as some observers think it could despite his relative obscurity, he will find it hard to sidestep the question entirely.

At the core of the problem is the attitude of many evangelical Christians, almost a third of whom dislike the idea of a Mormon president. That is particularly relevant in the early caucus state of Iowa and in the south, where the Republican nomination is often lost or won.

"It's a false religion and that's dangerous," said Warren Cole Smith, associate publisher of Christian news magazine World. "If either Romney or Huntsman were elected to the highest office in this country that would be like a shot in the arm for Mormonism."

Both candidates have indicated that they might bypass Iowa and focus instead on early states such as New Hampshire and Florida where evangelicals are less prevalent. The Mormon church itself refuses to engage in party politics, and will not comment on either candidacy. But the question of how the faith is perceived within America is close to its heart, as is therefore the presence of two Mormons in the race.

"There is a conversation going on, and church leaders see this as an opportunity to set the record straight and explain who we are," said Otterson.

What if Romney or Huntsman should go all the way to the White House? What would the church think then? "We are just waiting and seeing," he said.

A very American faith

The irony about the persistent distrust of Mormonism in America is that it is a quintessentially American religion. At its core is the belief that Jesus had made a visitation to America after his resurrection, converting a family of Israelites who had migrated there and establishing a messianic kingdom. That makes it the religious equivalent of the theory of American exceptionalism at the heart of much of the country's political discourse.

The church was founded in 1830 by Joseph Smith, son of a poor New England farmer. At 14, then living in upstate New York, he started having visions in which he was visited by God, Jesus and an angel called Moroni.

Moroni revealed to him a book, buried in a hill, made of golden plates and written in an ancient language by an Israelite prophet. Smith magically translated the Book of Mormon, which recounted the story of Jesus in America. From its inception, the church heavily emphasised the value of proselytising. It now has 14 million members and has spread across Latin America, Europe and Africa.

• This article was amended on 6 July 2011. The original referred to the belief that Jesus made a second coming to America after his resurrection. This has been corrected.