Most Americans are comfortable with Mitt Romney's Mormon faith, but they appear more comfortable with President Obama's religion—that is, unless they believe he's a Muslim.

New findings suggest that Romney's religion is unlikely to affect the election, according to a survey sponsored by the Pew Research Center for the People & the Press and the Pew Forum on Religion & Public Life. The vast majority of those who know Romney is a Mormon are either comfortable with Romney's religion (60 percent) or say it does not matter (21 percent). Just one-fifth said they are uncomfortable with Romney's Mormon religion.

Romney's religion is unlikely to change any votes, but it may lower enthusiasm for his candidacy. More than 90 percent of Republican voters who know Romney is a Mormon say they will vote for him. Among Republicans who say they are uncomfortable with his religion, however, only one-fifth say they strongly support him. That support is half that of other GOP voters (42 percent strong support).

In a recent speech about the shooting victims in Colorado, Romney gave a rare nod to faith.

The public appears fairly comfortable with President Obama's religion. But there is one major difference—the public's comfort with Obama's religion depends on whether they believe he is a Christian or a Muslim.

Just 12 percent of American voters say they are uncomfortable with Obama's religion, half the level of discomfort with Romney's Mormon faith. And while 21 percent said that Romney's religion "doesn't matter," only six percent said Obama's religion is irrelevant.

But the pattern changes for the 12 percent of voters who believe Obama is a Muslim. Only 26 percent of those who believe the President is a Muslim say that they are comfortable with Obama's religion. Two-thirds of those who believe Obama is a Muslim said they are uncomfortable with his faith.

Belief that Obama is a Muslim is most common among conservative Republicans (one-third). The number has risen to twice the percentage from October 2008, when 16 percent of conservative Republicans said Obama was a Muslim. Of Romney supporters, 30 percent believe Obama is a Muslim, compared to only six percent of Obama supporters.

The Pew survey suggests that evangelicals hold some paradoxical views on Romney's religion. Evangelicals are the most likely to say that it is important that the President hold strong religious beliefs (88 percent). Most evangelicals see the Mormon religion as "very different" from their own faith (63 percent). Unlike Mainline Protestants and Catholics, evangelicals are evenly split on whether Mormonism is a Christian religion. Yet, only one-fourth of evangelicals (23 percent) said they are "uncomfortable" with Romney's religion, about the same as for the average voter (19 percent).

Only half of Americans know Romney's religion. In an NBC Nightly News interview on Wednesday, Romney was asked if he was a "hidden man" because he does not talk about his family heritage because it involves Mormonism.

"I'm very proud of my heritage," Romney said. "Without question, I'm a member of the Church of Jesus Christ of Latter-day Saints. I'm proud of that. Some call that the Mormon Church, that's fine with me. I'll talk about my experiences in the church. There's no question they've helped shape my perspective."

Even if Romney were to speak more about his heritage and religion, the public may not hear him. More people know that Romney is a Mormon (51 percent) than know that Obama identifies himself regularly as a Christian (45 percent). Overall, 36 percent of the public says they "don't know" the President's religion (the same percentage that said they do not know about Romney's).

The poll was sponsored by the Pew Research Center for the People & the Press and the Pew Forum on Religion & Public Life. The survey, conducted June 28 through July 9, interviewed 2,973 adults. Most of the results discussed in the report refer to registered voters only.