Enlarge By Erich Schlegel, for USA TODAY On a typical Sunday morning, Diane and Stefan Mueller don't go to church. They often walk their dogs and take their son Kai to play in nearby parks. COMPARE CHANGES IN U.S. RELIGIONS OVER 2 DECADES COMPARE CHANGES IN U.S. RELIGIONS OVER 2 DECADES FAITH & REASON FAITH & REASON Join the conversation on religion, spirituality and ethics here. And catch up on interesting news with USA TODAY's

Cathy Lynn Grossman. THINKING ABOUT GOD THINKING ABOUT GOD About 15% of Americans say they have no religious identity -- but they don't all believe the same things. Their responses when asked about the existence of God:

Men: Women: Source: American Religious Identification Survey of 1,106 people who don't identify with any religion Americans who don't identify with any religion are now 15% of the USA, but trends in a new study shows they could one day surpass the nation's largest denominations — including Catholics, now 24% of the nation. American Nones: Profile of the No Religion Population, to be released today by Trinity College, finds this faith-free group already includes nearly 19% of U.S. men and 12% of women. Of these, 35% say they were Catholic at age 12. FAITH & REASON: Were Founding Fathers 'Nones?' "Will a day come when the Nones are on top? We can't predict for sure," says lead researcher Barry Kosmin. But if Nones, now 22% of all adults ages 18 to 29, continue to gain among young adults, to draw more people "switching out" from denominations and to replace more religious older people, researchers forecast one in five Americans will be Nones in 20 years. "Trends clearly favor this," Kosmin says. But he also notes, "There could be a Great Awakening (massive Protestant revival) or immigration may bring in more Catholic believers." Kosmin and Ariela Keysar of Trinity College, Hartford, Conn., directed three editions of the American Religious Identification Survey over 18 years. The 2008 ARIS (pdf), based on a sampling of 54,000 U.S. adults, also burrowed in for a closer look at 1,106 Nones, who answered extra questions about their beliefs and behaviors and views on God. ARIS: Most religious groups have lost ground in USA 'NONES': Now 15% of population The report finds: •Not all Nones are alike. Half (51%) still believe in God or a higher power. •Nones also are the only major U. S. faith group that's majority male. Even when girls grow up with unbelieving parents, they're more likely to find a faith as adults than their brothers. "Women are also less skeptical than men and less drawn to irreligious and anti-religious views. They are more likely to reject a secular upbringing," Kosmin says. "There is a lot of 'churning' going on but Nones gain much more from switching (people leaving religion) than from natural growth (children emulating unbelieving parents)," he says. •The percentage of atheist Nones — who say there's no such thing as God — hasn't budged in years. "It's not as though dozens of people at the Methodist Church read (atheist Richard) Dawkins and suddenly decided God doesn't exist," says Kosmin. "There are so many misconceptions about who the Nones are. They're not New Age searchers or spiritual or even hardened atheists," says Kosmin. "They're a stew of agnostics, deists and rationalists. They sound more like Thomas Jefferson and Tom Paine. Their very interesting enlightenment approach is like the Founding Fathers' kind: Skeptical about organized religion and clerics while still holding to an idea of God." One quirky fact: 33% of Nones claim Irish ancestry, although the U.S. Census says only 10% of the USA does. "We have no idea why," he says. "Maybe you could ask (Fox newscaster) Bill O'Reilly. In some way, researchers found Nones are very much like the overall, largely religious, U.S. population. There's no statistical difference on education, or income or marital status. They are just as likely to be divorced as anybody else. "Nones are not a fringe group anymore and are now part of Middle America. They're present in every socio-demographic group, Keysar concludes in their report. READERS: Is your religion — or lack thereof — an important part of your identity? Respectfully share views and experiences below: Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more