The United States has a long tradition of separating church from state, but an equally strong tendency to mix religion and politics. 

Unlike many countries, the United States is an overwhelmingly religious nation. Americans generally are quite at ease with public displays of faith and most approve of political leaders expressing their religious beliefs.

Every American president since George Washington has taken the oath of office by placing his hand on the Bible and pledging to carry out his duties by saying, "So help me God." Some of the country's powerful political and social movements -- from the abolition of slavery and the push for civil rights to today's struggles over abortion and homosexual marriage -- have sought moral support from religion.

But many analysts note that while most Americans like their politicians to be men and women of faith, they are deeply suspicious when religious institutions seek to influence political parties, campaigns and elections.

Constitutional expert Vincent Munoz of Tufts University in Massachusetts says the debate over the separation of church and state originated with the nation's Founding Fathers. "Individuals like George Washington thought that a self-governing nation needed self-governing citizens and that religion was instrumental to cultivate the moral character that individuals needed for self-government and therefore the State should endorse religious beliefs," says Munoz. "Someone like James Madison thought you may need religion to support a republican government [i.e., a democratic republic], but you don't need government to support religion."

Munoz says that when the Founders incorporated freedom of religion in the First Amendment of the Constitution, their intent was to find a way for citizens of different faiths to live in harmony. "One thing almost all of the Founders agreed on was that we shouldn't coerce religious beliefs or practices. And [what] they meant by that [was that] no citizen should lose civil rights on account of religious belief or the lack of religious belief," says Munoz. "There should not be a religious test for office. That's in the federal constitution. You didn't have to be a specific denomination to hold federal office, so no punishment on account of religious beliefs, no loss of civil liberties on account of religious beliefs."

Faith at the Ballot Box

While religion has always mattered in American politics, some analysts say that in recent years, it has taken on a more prominent role in national elections.

John Green, of the Washington-based Pew Forum on Religion and Public Life, points to President Bush's victories in 2000 and 2004, for example, which in part were due to his successful appeal to conservative religious voters. But Green says voters casting ballots in keeping with their religious beliefs dates back decades.

"Starting about 30 years ago, religion began to become much more prominent in elections, in campaigns and in public life than it had been in the previous 30 years. And the largest reason for that were the changes in the questions that Americans have debated, like abortion and marriage and gay rights," says Green.  "And in recent times, issues have included the Iraq War, poverty and questions concerning the environment. President Bush in many ways represents the most recent part of that trend. But it really began with Jimmy Carter [in 1976], with Ronald Reagan [in the 1980's] and the different presidents in between."

Green says America's two leading political parties - - the Democrats and the Republicans - - are often at loggerheads over social issues because of their different religious constituencies. "In the Republican Party, it tends to be white Christians, particularly white evangelical Protestants, but also Christians of other backgrounds. The Democrats have a more complicated religious coalition that includes African-American Protestants, Hispanic Catholics, liberal Christians, Jews, Muslims and Hindus, as well as non-religious people," says Green.

Green says the Republicans tend to talk more openly about religious questions because their coalition is not as diverse. In the Democratic Party, politicians do talk about religion, says Green.  "But they are much more cautious because of the religious diversity of the Democratic Party."

The Immigrant Connection 

Political scientist Edward Sidlow of Eastern Michigan University says America's religious scene has changed significantly since the founding of the Republic and could intensify the debate over the role of religion in politics.

"It was fairly easy when the population was small, the land mass was small [i.e., the U.S. was small] and the population was homogenous to make sense where religion should stop and start with respect to the public square. The public square has become a very large, heterogeneous community with different people bringing different religious needs and cultures into their lives. And so you do run into a problem with figuring out where religion stops and starts inside and outside of the governmental and political arena," says Sidlow.

But many constitutional experts, among them Vincent Munoz of Tufts University, argue the separation of church and state crafted by the Founding Fathers ensures that religion is not saddled with problems that come with political partisanship. "When the Constitutional Convention put in the provision to say no religious test for office, that was objected to by people who opposed the Constitution. One of the arguments was that if we don't have a religious test for office, Jews or Catholics or Muslims might be elected," explains Munoz.

Munoz adds, "James Madison's response was,'Well, if the people of America want to elect a Jew or a Muslim or a Catholic for office, that's fine.' And so, yes, it is true that at the time of the founding we were a more homogenous nation, but it doesn't mean that the Founders didn't anticipate much of the religious diversity we enjoy today in America." 

And most analysts says the role of religion in public life will likely continue to be an integral part of American politics.

This story was first broadcast on the English news program, VOA News Now. For other Focus reports click here.