Poll shows religiously unaffiliated Americans are now a plurality; professor says it's happening in rural America too

Though most Americans are Christians, their share of the adult population is waning, and more than ever say they don't follow any religion, according to polling from the Pew Research Center.

About 63 percent of respondents self-identified as Christians, down 12 points from 2011. "In addition, the share of U.S. adults who say they pray on a daily basis has been trending downward, as has the share who say religion is 'very important' in their lives," Gregory A. Smith reports. The decline in religion is concentrated among Protestants: 40% of respondents identify as Protestant, down 4 points in the past five years and 10 in the last 10.

About one-third of Americans identify with no religion, and say they're atheists, agnostics, or "nothing in particular" when asked about their religious identity. "If the unaffiliated were a religion, they’d be the largest religious group in the United States," Santa Clara University religious-studies professor Elizabeth Drescher told The Associated Press. Religiously unaffiliated Americans were once concentrated in urban, coastal areas, but are increasingly common in rural areas, said Drescher, who wrote a book about the spiritual values of the "nones."

The findings underscore a March report from Gallup showing that Americans' membership in houses of worship fell below half the population for the first time since Gallup's tracking began in 1937.

Paul Prather, a columnist and evangelical pastor in Kentucky, has theories on why religious affiliation is waning. The internet exposes us to many different belief systems and makes it easier to connect with others online instead of seeing a local church as a social hub, he wrote. And younger Americans tend to distrust all types of institutions, including churches.