(CBS News) The words "In God We Trust" can be found on all our currency, a reflection of the importance of religion in American lives. At least the lives of many of us, but not ALL.

It's not just in Newtown, Connecticut, but in churches and synagogues - and any other building of faith - the question "why" is being asked over and over this morning.

In times of both heartache and happiness, we turn to our faith for guidance and comfort. But increasingly, how we think about our faith is changing.

According to a new study by the Pew Forum on Religion and Public Life, the nation's spiritual landscape may be becoming a little LESS religious.

Some 45 million people, or one-fifth of the U.S. adult population, now say they belong to no church in particular.

Six percent of them are either atheist or agnostic.

"There's a yearning to find like-minded people, to be able to have a conversation that's not taboo," said Red McCall, president of an atheist group in the buckle of the Bible Belt - Oklahoma City - whom we met last month.

In just the past three years, membership in the Oklahoma Atheists has jumped from just 300 members to well over a thousand.

Shelly Rees, a college professor, in one of them. She feels the public mood on atheists - even here - has softened.

"There were still people when we were marching in the parade at Halloween yelling, 'You're going to hell,' and stuff like that," said Rees. "But there were more people who weren't, and I think that's going to keep going. I think that's the trend."

Researchers call them "The Nones" - those who check the "none" box when asked to describe their religious affiliation.

And they've more than doubled since 1990.

Is the nation becoming more secular? "Maybe, a little bit," said Cary Funk, the senior researcher on that Pew Study. Funk says it's a complicated question, because being unaffiliated isn't necessarily the same as not having faith.

"Sixty-eight percent of the unaffiliated say they believe in God or a universal spirit. More than a third describe themselves as spiritual people, but not religious people," Funk said. "And a good portion pray, at least daily."

So if it's not God, or the thought of a higher power that's turning people off, what is?

The study suggests it's organized religion - with respondents overwhelmingly saying many organizations are too focused on money, power and politics.

Protestants have suffered the greatest decline. They now account for just 48 percent of religious adults, making it the first time in history that the United States doesn't have a Protestant majority.

Evangelical churches aren't immune, either. The megachurches once bursting at the seams are a little less mega than they used to be.

"We're seeing church attendance being much more inconsistent than I've ever seen it in my entire life," said Ed Young, Senior Pastor of the Fellowship Church based in Dallas. He's hardly conventional - even preaching a sermon with his wife while sitting on a double bed.