If you could erase one moment from Sen. Barack Obama's White House campaign, which would you choose?

That's an easy question for evangelicals, Catholics and other religious believers who back Obama. Most would happily erase all evidence of his speech last spring to a circle of insiders behind closed doors in San Francisco. For those who have ignored national news in 2008, Obama talked about meeting voters in rural Pennsylvania, where hard times have crushed hopes and fueled resentments.

"So it's not surprising then that they get bitter," he said, that "they cling to guns or religion or antipathy to people who aren't like them ... to explain their frustrations."

Welcome back to the "culture wars," all you politicos who hoped and prayed that talk about "values voters" and "pew gaps" would disappear. Instead, Republicans have been chanting this mantra -- "bitter," "cling," "God" and "guns" -- for months.

"In small towns, we don't quite know what to make of a candidate who lavishes praise on working people when they are listening, and then talks about how bitterly they cling to their religion and guns when those people aren't listening," said Alaska Gov. Sarah Palin, as she hit the national stage. "We tend to prefer candidates who don't talk about us one way in Scranton and another way in San Francisco."

It's crucial to know that this kind of cultural warfare has evolved throughout American history, said Todd Gitlin, who teaches journalism and sociology at Columbia University in New York City. The issues change from campaign to campaign, along with the fierceness of the fighting. But cultural and religious issues always matter.

"The culture wars always matter because Americans vote not simply, and not even necessarily first, for what they want but for whom they want. And whom they want is a function, in part, of who they are and how they ... want to think of themselves. In a word, what kind of culture they embody," said Gitlin, during a pre-election forum sponsored the Pew Forum on Religion and Public Life.

These battles over symbols and substance are rooted in the fact that America was created "as the fruit of an ideology, not a nationality." Thus, he stressed, "America is a way of life, in other words, a culture. So culture wars are as American as egg foo yung and tacos."

But what are these "culture wars" really about? From Gitlin's point of view, the fighting is not a simple standoff between "religion and irreligion," because there are religious voices on both sides. Most would agree, he said, that these clashes pit "forces of modernization" against "forces of tradition." Often, this seems to pit small-town values against cosmopolitan culture, or red-zip-code preachers against blue-zip-code professors.

From his perspective on the left, he said, all of this looks like an "ongoing fight ... between the Enlightenment and its enemies." Seriously, he said, "American has to outgrow this childish negation of reason."

For Americans on the other side of the "culture wars," that kind of talk sounds rather condescending, said Yuval Levin, who leads the Bioethics and American Democracy Project at the conservative Ethics and Public Policy Center.

From the right, this cultural warfare resembles a "war of two populisms, what we might call in very broad terms, cultural populism and economic populism," said Levin.

As a rule, the American left has been effective when it comes to appealing to the economic passions and resentments of average Americans. The right, meanwhile, has been stronger -- especially since the earthquake that was the 1960s -- when appealing to old-fashioned values of faith, family and unashamed patriotism.

In this election, economic fears may certainly triumph over concerns about traditional "culture wars" issues such as abortion, gay rights, the role of religion in public life and the moral content of popular entertainment.

Nevertheless, stressed Levin, Obama's "bitter" speech proved that cultural questions are always lurking in the background. The candidate said, right out loud, what heartland conservatives truly believe San Francisco liberals think about them.

That mistake may not matter this year, but it isn't a wise long-term strategy for a president.

"In America, unlike in Europe, cultural populism has generally been a lot more powerful than economic populism," said Levin. "Americans don't resent success. They don't assume that corruption is the only way to the top, but they do resent arrogance and especially intellectual arrogance."