Much of the switching in religious identity in the United States over the past several years occurred among the “nones,” specifically Americans who identify as agnostic or as “nothing in particular.” But the Christian landscape hasn’t remained static in the meantime.

Though academics have long wondered whether the US will follow the secularizing trend found in most of Europe, the greatest shifts among believers have occurred within Christianity, not away from it.

The three-wave Cooperative Congressional Election Study (CCES)—which surveyed the same individuals in 2010, 2012, and 2014, and started with 9,500 respondents—reveals how few Catholics and Protestants have changed affiliations and how many have moved from one denomination (or nondenomination) to another.

During this period, Catholics remained pretty attached to their tradition; they were about half as likely as Americans on average to change their affiliation: 8.8 percent vs. 18.9 percent. When Catholics do switch, they largely shift toward having no faith, with 6.4 percent switching to agnostic, atheist, or “nothing in particular.”

For Catholics, transitioning to another religious tradition is extremely rare. Of the 2,112 Catholics in the CCES sample, fewer than 50 left: 39 became Protestants, 6 became Orthodox Christians, and 3 became Buddhists.

Protestants—the largest religious tradition in the US, making up 42 percent of Americans in the 2010 CCES panel—show similar patterns to their Catholic counterparts.

Protestants largely stay Protestant, defecting at similar rates as Catholics during the four-year period: 8.8 percent vs. 9.1 percent. The vast majority of those who leave Protestantism also become nones. Of those who identified as Protestants in 2010, 7.4 percent became nones by 2014, with 5.7 percent identifying as nothing in particular.

Though overall Protestant figures remain relatively steady, there is a tremendous amount of turbulence inside Protestantism.

While the Catholic Church is essentially unified, Protestantism is subdivided into a thicket of denominational traditions for Americans to switch between. The CCES lists 13 Protestant subgroups; some, like “Lutheran,” are composed of multiple denominations.

About 16 percent of all Protestants who stayed Protestant actually changed subgroups during the four years of the survey. Together with the 9 percent of Protestants who left, that means approximately one in four Protestants in 2010 had a different affiliation by 2014.

Full story at Christianity Today.