A new survey from the Pew Research Center indicates that the number of American Christians is declining, while the number of Americans who don't identify with any organized religion is increasing. The drop is occurring throughout all age ranges, but it's happening most rapidly with young adults.

The United States still has more Christians than any other country, but that number has gone down by almost 8% since 2007. Additionally, Christianity in the US has become increasingly diverse. The poll points out, "Racial and ethnic minorities now make up 41% of Catholics (up from 35% in 2007), 24% of evangelical Protestants (up from 19%) and 14% of mainline Protestants."

Religious intermarriage is also increasing, which partially accounts for the drop in religious affiliation. There are now around 56 million religiously unaffiliated Americans, sometimes referred to as religious "nones." In 2007, 25% of the “nones” referred to as themselves atheists or agnostics. That number has grown to 31%.

Pew's Religious Landscape Studies were designed to get answers that the US census doesn't provide. "Surveys of the general public frequently include a few questions about religious affiliation," the study explains, "but they typically do not interview enough people, or ask sufficiently detailed questions, to be able to describe the country’s full religious landscape."