Some 15 percent of Americans claim no religious affiliation, up from 8.2 percent in 1990, according to Trinity College's American Religious Identification Survey, released in March. Also, the American Humanist Association claims 20,000 financial supporters. That marks a doubling from five years ago, says spokeswoman Karen Frantz.
Moreover, signs point to non-believers seeking fellowship as never before. During the first five months of 2009, 95 new atheist groups have formed through meetup.com, bringing the US total to 372. That's up from 59 in 2005, says Blair Scott, director of national affiliates for American Atheists, a networking and advocacy organization. Known parenting groups for nonbelievers have proliferated from just one in 2005 to 33 in 2009, adds Mr. McGowan, the author.
The intersection of the two trends is evident across the United States. For example, the North Alabama Freethought Association, which has grown from 50 members in 2006 to 350 today, drew 30 people to a camping event in May and runs regular outings to visit caves or other science-related sites.
"It used to be that these atheist groups ... met almost in hiding," says American Atheists spokesman David Silverman. "Now they're doing a lot more stands at town parties, a lot more trash pickups, a lot more blood donations – a lot more stuff that gets their group out and noticed."