Even though the government in the United States is secular, religion has almost always played an important role in national elections. Until recently, a person's denomination was the leading indicator of how he or she would vote. Mainline, northern Protestants often voted Republican, while Jews and Catholics tended to vote Democratic. But now there's a new "religion gap" in American politics, and it's one in which religious commitment, not just identity, is playing a crucial role.

The new gap is between those who say they attend worship services frequently, and those who do not. According to a recent survey conducted by the Pew Research Center, 63 percent of Americans who formally worship more than once a week vote Republican, while 62 percent of those who say they hardly ever attend worship services vote Democratic. Mark Silk, the director of the Center for the Study of Religion in Public Life at Trinity College in Connecticut, says the tendency of non-religious voters to identify with the Democratic party isn't new, but that frequent worshippers didn't begin voting solidly Republican until recently.

"Looking particularly at the votes for Congress, which occur every two years, you see a huge increase in this religion gap particularly from '92 to 2000, and a slight increase from the 2000 to the 2002 election," he said.

Mark Silk's evaluation is based on exit polling data that doesn't include questions about why voters chose the parties that they did. But given that people who attend weekly services tend to stress personal morality over social responsibility, he says it isn't difficult to theorize about why the political gap between the very religious and the not-so-very religious got wider in the 1990s.

"The big political issue between Democrats and Republicans in the period of this greatest run-up is Bill Clinton and questions surrounding his personal morality and the Lewinsky affair and impeachment," said Mr. Silk.

But the new religion gap making headlines is a gap of extremes. The reality is that most Americans don't attend worship services more than once a week, nor do they avoid worship services entirely. The overwhelming majority of voters say they're "spiritual," and that they attend services "occasionally." These voters, it seems, are still up for grabs. But according to Amy Sullivan, a Princeton University researcher who specializes in religion and politics, the new religion gap has caused many Democratic leaders to fall into the trap of believing that if you care about religion, you don't care about the Democratic Party.

"I don't think that many Democratic candidates understand the extent to which the people who give them their support are religious themselves," she said. "I think one of the things that has happened over the last few decades is that with the rise of the Religious Right and organizations like the Christian Coalition, we had this perception that religion and politics meant 'conservative Christians,' 'far-right fundamentalists,'" she said.

According to Amy Sullivan, this misconception has already manifested itself in the Democratic campaign, and she can think of a couple of examples.

"John Kerry, whenever he's asked about religion, immediately has sort of a Pavlovian reaction and spits out 'separation of church and state,' whether or not it's actually relevant," she said. "And it's true that a lot of Democratic voters care very deeply about the separation between church and state. But it sort of waters down the meaning of that principle when it's used as a catch-all answer. The piece of Howard Dean's stump speech that he used throughout the fall, and has wisely dropped, where he complains that too often voters in the South vote based on 'God, guns and gays.' Which is an unnecessary line that wasn't going to win him votes from anybody, but had a very good chance of alienating a heck of a lot of people for whom God is quite important."

Of course, in the case of Governor Dean and Senator Kerry, there may be more at work than just a misunderstanding about what the new religion gap means for American politics. Both candidates are from New England, a part of the United States that has a long history of keeping religion private. In that respect, these "Yankees" are different from Southerners, many of whom go to church frequently and wear their religion on their shirtsleeves. So it shouldn't be surprising that more openly religious Republican candidates, beginning with Ronald Reagan in 1980, appeal to these southern voters, who had been solidly Democratic for more than a century. In the presidential election of 2000, every southern state except Maryland voted for George W. Bush, who is an evangelical Christian.