After eight years of a “faith-based’’ United States presidency, the mere mention of “nonbelievers” in Barack Obama’s Inaugural speech marked a stark departure from his predecessor.

George W.Bush, after all, rose to power with help from a highly motivated bloc of evangelical Christians. As president, many of his most important decisions, including the Iraq invasion and limits on stem cell research, were influenced by faith, prayer and advice from religious leaders.

But the infusion of religion in American life and politics runs much deeper than the presidency of George W.Bush. It started with the Founding Fathers, though historians note that some of them were not exactly diligent churchgoers. President Obama himself professed a strong Christian faith on the campaign trail. And President Ronald Reagan even proclaimed that “morality’s foundation is religion; religion and politics are necessarily related.’’

But what then of President Obama’s“nonbelievers?’’Are they immoral? Not in Scandinavia.

While America’s Founding Fathers pioneered the separation of church and state, Denmark and Sweden may have perfected it.

Phil Zuckerman, an American sociologist who has studied the waning influence of religion in those two nations, told The Times’s Peter Steinfels that they contradict the assumption that without faith a society becomes“rampant with immorality, full of evil and teeming with depravity.’’Instead, Mr.Zuckerman encountered“a markedly irreligious society that was, above all, moral, stable, humane and deeply good.’’

And while American politicians often mention God or quote the Bible, a Danish pastor told Mr. Zuckerman that“the word‘God’is one of the most embarrassing things you can say.”

“You would rather go naked through the city than talk about God,’’he said.

Across the North Sea, in England, it is the nonbelievers who are vocal. As Sarah Lyall reported in The Times, London buses have been carrying advertisements that read:“There’s probably no God. Now stop worrying and enjoy your life.’’

Supported by Richard Dawkins, a scientist and author of“The God Delusion,’’this Atheist Bus Campaign has met with strikingly little controversy. Even the Methodist Church praised it for stimulating discussion. But then, like Scandinavia, England is a“deeply secular’’nation, as Ms.Lyall wrote.

Even in America, a land sometimes caricatured for its preachy politicians and God-fearing voters, the real picture may be more nuanced. In a survey last year conducted by the Pew Forum on Religion and Public Life, nearly half of Americans said they believed that atheists could go to heaven (“dragged there kicking and screaming, no doubt,’’as Charles M.Blow wrote in The Times).

Meanwhile, a nascent movement of nonbelievers is aiming to counter the powerful political influence of America’s religious right wing. The Secular Coalition of America hopes to attract a base of about 30 million voters, its director, Lori Lipman Brown, told Samuel G.Freedman of The Times.

For now, however, the coalition consists of only two staff members. Atheists, perhaps, are a bit leery of congregations.