Editor's note: Listen to the CNN Radio interview with Robert Putnam and David Campbell, authors "American Grace: How Religion Divides and Unites Us": http://podcasts.cnn.net/cnn/services/podcasting/audio/cnnprofiles/cnnprofilesa02-20-2012.mp3

By Katie Glaeser and Emma Lacey-Bordeaux, CNN

Forget the economy. Debate about contraception, abortion, same-sex marriage, even Satan, has attracted just as much attention on the presidential campaign trail in recent weeks.

While culture war issues make headlines galore, an exhaustive study of Americans' religious attitudes shows the public as a whole might not find the debate so enticing.

Robert Putnam and David Campbell are authors of the recent book "American Grace: How Religion Divides and Unites Us" and say that Americans have a knack for being able to disagree about hot button issues without being disagreeable.

"America is very unusual in being able to live comfortably with the people we disagree with," says Putnam, a Harvard University professor who also wrote the book "Bowling Alone."

Putnam and Campbell, of Notre Dame University, spent several years surveying thousands of Americans, seeking to understand how voters deal with religious differences.

Their portrait of the American faithful does reveal some rising tension. Putnam and Campbell found that the nation has grown increasingly polarized as more people either strongly identify with a particular religion or avoid organized religion altogether. But this polarization doesn't always mean conflict.

"If you only read the newspapers, you'd think that Americans really were at each others throats when it comes to religion" Campbell says.

To explain how Americans avoid fighting over the hot button issues that attract major heat at the national level, the authors point to what they call the "Aunt Susan effect.”

"That's the person in your family whom you know is destined for heaven even though she's of a different faith than you," Campell says. Americans tend to become more tolerant about different ideologies and religions when they know someone who subscribes to them.

Putnam says that this mingling has increased through friendships and marriage "so there are a lot of Aunt Susans around, more than there used to be and that in a way has offset this debate we're having in the public arena about religion."

Through their survey of roughly 4,000 randomly selected Americans, the two found that views of specific religious groups have shifted. "It turns out that the most popular religious groups in the U.S. today are Jews, followed by Catholics, which is amazing," Campbell said. "Fifty to 100 years ago those groups would've been near the bottom of that ranking."

When John F. Kennedy, a Catholic, ran for president a half-century ago, he faced voters whose opinions on his religion ran from uncertain to hostile. Today, many Americans harbor similar feelings toward Muslims and Mormons. The authors say those views help explain the relative silence from candidate Mitt Romney on his Mormon upbringing and faith.

CNN Radio's John Lisk asked Putnam and Campbell about another presidential contender, Richard Nixon, who appealed to the right during the primary but won the general election by winning many moderate voters. Applying that model to the current race, Campbell says devout Catholic Rick Santorum may have overplayed his hand in voicing strong conservative positions on social issues.

"Young people are way more liberal on homosexuality and contraception," Putnam says. "That's where Santorum is in trouble."

The authors found the nation has increasingly tolerant views with regard to homosexuality and Putnam says that "Santorum has put himself in a small minority" with some of his incendiary statements about gays.

At the same time, Putnam and Campbell say they found a new strain of conservatism emerging in the country. "Supporters of the Tea Party not only want to shrink government, but it's a group who has a particular view of how government and religion are intertwined," Campbell said. "That's historically unusual."

It's also unpopular, the authors say. The alliance between one political party and organized religion has provoked many believers to walk away from religious institutions, Putnam says. "They are fleeing the church because they are so opposed to this merger," Putnam said.

At the same time, the authors say more religious leaders are deciding to back away from politics. By halting "political sermonizing," the authors say faith leaders hope to draw and retain congregants.

But don't expect culture war issues to fade in the GOP primaries.

The GOP base rewards candidates for moving "toward the most conservative end of the spectrum religiously, all competing to be the most conservative on those issues," Putnam said. "That defines the primary campaign."