New research from Barna Group reveals that U.S. teens are more than twice as likely as adults to identify as atheists.

Some 14 percent of U.S. respondents aged 13 to 18 self-identify as atheists, compared to about 6 percent of adults. The survey was part of Barna’s recent report on Generation Z, which Barna defines as those born from 1999 through 2015.

The percentages of teens identifying as religiously unaffiliated (14 percent) and agnostic (8 percent) are similar to the shares of millennial and Gen X adults in those categories. However, Barna calls the rise in atheism among Generation Z a “glaring difference.”

Some 14 percent of U.S. respondents aged 13 to 18 self-identify as atheists, compared to about 6 percent of adults.

Barna also documents a decline with each successive generation in the percentage of Americans holding a biblical worldview. Ten percent of Boomers have a biblical worldview, compared to 7 percent of Gen X, 6 percent of millennials, and 4 percent of Gen Z.

Barna defines a biblical worldview as agreement with these commonly held Christian beliefs: absolute moral truth exists; the Bible is totally accurate in all the principles it teaches; Satan is a real being or force, not merely symbolic; a person cannot earn their way into heaven by trying to be good or do good works; Jesus Christ lived a sinless life on earth; and God is the all-knowing, all-powerful creator of the world who still rules the universe today.

“Many in Generation Z, more than in generations before them, are a spiritual blank slate,” Barna concludes. “They are drawn to things spiritual, but their starting point is vastly different from previous generations, many of whom received a basic education on the Bible and Christianity. The worldview of Gen Z, by contrast, is truly post-Christian.”