If Democrats prevail in the Nov. 6 presidential election, it may be for a surprising reason: because churchgoing has declined in America. Millions who stay home Sunday morning are the strongest backers of liberal politics.

New research by the Pew Forum on Religion and Public Life says the swelling number of secular Americans, who overwhelmingly vote Democratic, has risen to equal the shrinking number of white evangelicals, who overwhelmingly vote Republican.

In a report titled "Nones on the Rise," Pew said churchless Americans (those who answer "none" when asked their religion) now are the largest faith category in the Democratic Party base, comprising one-fourth of it. White mainline Protestants make up 14 percent of the base, along with white Catholics, 13 percent, and black Protestants, 16 percent. The report said:

"In recent elections, the religiously unaffiliated have become one of the most reliably Democratic segments of the electorate ... . In 2008, fully three-quarters of the religiously unaffiliated voted for Barack Obama over John McCain. In 2008, religiously unaffiliated voters were as strongly Democratic in their vote choice as white evangelicals were Republican ... . The religiously unaffiliated are heavily Democratic in their partisanship and liberal in their political ideology."

Moreover, the Pew report says the Democratic Party is likely to gain ground in the future, because younger Americans are dropping out of churches while conservative oldsters are dying off. Thus the secular tide will rise.

"One-fifth of the U.S. public -- and a third of adults under 30 -- are religiously unaffiliated today, the highest percentages ever in Pew Research Center polling," it said.

Since World War II, religion has dwindled in Europe, Canada, Australia, Japan and other advanced societies. At first, America seemed an exception to the secular trend, but now it has joined the shift. The number of U.S. adults with no church preference has soared to nearly 50 million. Traditional, well-educated, "mainline" Protestant faiths have suffered decline since the 1960s. Also, an estimated 20 million have drifted from Catholicism, so one-tenth of American adults are ex-Catholics.

We've never understood why white evangelicals are politically conservative. Jesus taught only compassion -- help the underdog, tend the sick, feed the hungry, clothe the needy, work for peace -- all qualities fitting the Democratic Party's agenda. It's puzzling that fundamentalists don't align politically with the values of Jesus.