By Dan Gilgoff, CNN.com Religion Editor

(CNN) - Americans have limited knowledge of the presidential candidates’ religious faith, but their concerns about the candidates’ respective religious beliefs are unlikely to play a major role in the 2012 race, according to a Pew survey released Thursday.

Most Americans, 60%, know that presumptive Republican presidential nominee Mitt Romney is a Mormon; he would be the first member of the Church of Jesus Christ of Latter-day Saints elected to the White House. Among those who are aware of Romney’s religion, 81% say that they are comfortable with it or that it doesn’t matter to them.

At the same time, 32% of Americans don’t know that Romney is Mormon, and another 9% identify him as the member of another tradition, the Pew survey found. Earlier surveys have suggested that those who don’t know that Romney is a Mormon are less likely to vote for a Mormon candidate.

The Pew survey showed that only 49% of Americans identify President Barack Obama as Christian, though that number has grown from 38% two years ago.

Obama has repeatedly talked about his Christian faith, and his relationship with his controversial former pastor, the Rev. Jeremiah Wright, was a major political liability during his 2008 presidential campaign.

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The Pew survey found that 17% of registered voters think Obama is a Muslim, while 31% say they do not know the president’s religion.

Thirty percent of Republicans say Obama is Muslim, Pew found, about twice as many who said that during the 2008 campaign.

The national survey was conducted from June 28 to July 9 among 2,973 adults, including 2,373 registered voters, by the Pew Research Center’s Forum on Religion and Public Life and the Pew Research Center for the People and the Press. The margin of error is plus or minus 2.1 percentage points.

Despite misunderstandings about the faith of the candidates, the Pew report said that views of the presidential contenders’ religious identifies were unlikely to shape the election in a major way.

“Along religious lines, white evangelical Protestants and black Protestants, on the one hand, and atheists and agnostics on the other, are the most likely to say they are uncomfortable with Romney’s faith,” the Pew report said. “Yet unease with Romney’s religion has little impact on voting preferences.”

“Republicans and white evangelicals overwhelmingly back Romney irrespective of their views of his faith,” the report said, “and Democrats and seculars overwhelmingly oppose him regardless of their impression.”

At the same time, the comfort level with Romney’s religion appears to have an impact on enthusiasm for the former Massachusetts governor.

“Among Republican and Republican-leaning voters who say they are comfortable with Romney being Mormon, 44% back him strongly,” the Pew report said. “Among those who are uncomfortable with it, just 21% say they back him strongly.”

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When it comes to Obama’s religion, just 45% of voters say they are comfortable with it. But among the half of Americans who correctly identify Obama as a Christian, comfort level with his beliefs is much higher: 82%.