The percentage of Americans who call themselves Christian has dropped significantly since 2007, according to a new survey by the Pew Research Center. Mainline Protestants and Catholics have experienced the largest losses (-3.4 percent and -3.1 percent, respectively), Evangelicals the smallest (-.9 percent, just over the margin of error). While the dip in Christian affiliation has occurred across all age cohorts, the younger you are, the more likely you are not to identify with any religious tradition. While non-Christian faiths saw modest bumps in affiliation (+.5 percent for Muslims, +.3 for Hindus), no group grew more than the "nones," who make up nearly 23 percent of the population--a gain of 6.7 percent since 2007. There are now more nones than Catholics.

Mainline Protestants have suffered the largest losses in absolute numbers--there are 5 million fewer today than there were in 2007. Like the Mainlines, Catholics are decreasing as a percentage of the population and in terms of raw numbers. Pew Research notes that Catholic losses may total no more than 1 million, accounting for margins of error. A number of studies over the past twenty-five years have come up with differing estimates of the size of the U.S. Catholic population over time. Some have found steadier numbers than Pew Research (until about 2010-2012). But one of those surveys did not interview as many young people as Pew did, and interviewed more Hispanics. The losses found by this Pew Research study--based on a sample size of 35,000--track closesly with the organization's monthly polls.

The decline among Christians comes at a time when they are becoming more ethnically diverse. Since 2007, Catholics, Mainline Protestants, and Evangelicals all saw their ethnic and racial minority populations grow by about 5-6 percent. Today 41 percent of Catholic Americans are members of racial and ethnic minorities.

Accompanying the shrinking of American Christianity is an increase in intermarriage. Of Americans who got married since 2010, about 40 percent of them married someone from a different religious tradition, double the percentage of those who married before 1960. This phenonenon is, accoring to Pew Research, tied to the rise of the nones. "Nearly one-in-five people surveyed who got married since 2010 are either religiously unaffiliated respondents who married a Christian spouse or Christians who married an unaffiliated spouse." The same could be said of just 5 percent of those who married before 1960.

So what's driving this decline? Pew Research identifies generational replacement (young adults are not too taken with organized religion), along with losses among older Americans. About one-third of Millennials in their late twenties and thirties, for example, now say they are not religious--a 9 percent jump since 2007. About 25 percent of Generation Xers say the same (a 4 percent increase since '07).

Religious switchers are also part of the story. "If all Protestants were treated as a single religious group, then fully 34 percent of American adults currently have a religious identity different from the one in which they were raised"--an increase of six points since '07. Religious nones have seen the largest gains from religious switching. Almost one-fifth of Americans were raised in a religious tradition and now say they belong to none. About 4 percent of Americans moved in the opposite direction.* But for every one of those there are more than four religious dropouts. Religious switching has hit Catholicism especially hard. For every person who converts to Catholicism, six more leave.

For Catholics, these findings are another in a series of recent wake-up calls. For years conservatives have blamed the decline of Mainline Protestantism on alleged secular accommodation. Perhaps it's time to rethink that theory. The climate for religion the United States is  changing rapidly. Converts are not keeping up Catholic numbers. Young people are rapidly losing interest. Latinos probably won't save the U.S. church. There's no point in seeking comfort in margins of error, another tradition's greater losses, or anecdotes. Winter is coming. It may already be here.

_{* This sentence has been corrected. It originally misstated the number of Americans who were raised as nones but now identify with a religious tradition. Nine percent of Americans were raised without any religious affiliation. About half of them have joined the ranks of the religiously affiliated.}