As President Barack Obama and Mitt Romney make their cases to lead America, their speeches are often infused with religious overtones.
It's a strategy that needs to be played carefully, and can have an impact on whether or not a person gets elected, according to Christopher Chapp, assistant professor of political science at the University of Wisconsin-Whitewater.
Chapp has published a new book, "Religious Rhetoric and American Politics: The Endurance of Civil Religion in Electoral Campaigns."
In it, he explores religious communication in American presidential races and the difference it makes in how people view candidates and vote on Election Day.
"There may be a wall separating church and state, but not religion and politics," Chapp said. "Voters watch how candidates communicate about religion and can see that as a sign of a candidate's morality. There was a lot of attention on 'values voters' during the Bush-Kerry race in 2004, and I wanted to see if religious rhetoric influences voter behavior."
For his book, Chapp analyzed more than 1,300 presidential stump speeches given from 1980-2008. He also conducted a national survey, seeing how voters responded to fictitious political ads that used varying degrees of religious tones.
"In the United States, candidates have to appeal to diverse constituencies," Chapp said. "Few candidates actually talk about their specific faith. What seems to have sway is civil religion - when candidates talk in a non-denominational way about God, faith, spirituality, and the connection of those concepts to America."
Successful presidential candidates from both parties have found ways to incorporate religious sentiment - from Ronald Reagan's "city on a hill" to Obama's descriptions of social policy.
"In general, civil religion improves a candidate's favorability," he said.
Surveys revealed nearly 80 percent of those polled agreed Americans are "blessed" with special opportunities, about half agreed being American is a "sacred" responsibility, and 30 percent said the U.S. Constitution is a "holy" document.
Yet, a growing number of Americans identify themselves as non-religious.
"These folks are turned off by religious rhetoric, even subtle phrases. At the same time, many people are very willing to admit apprehension about voting for an atheist for president," Chapp said. "In the minds of many voters, there's still a connection between God and America. For candidates, it's all about striking a balance."
Religious Rhetoric and American Politics: The Endurance of Civil Religion in Electoral Campaigns is published by Cornell University Press.