SDSU psychology professor Jean Twenge and her team found that 75 percent of high school seniors say religion is not important to them. She suggested that the decline in religious activity is linked to a rising individualism in American culture.
The study comes on the heels of research released two weeks ago by the Pew Research Center that showed the portion of U.S. population as a whole that's not affiliated with any religion has climbed from around 16 percent in 2007 to nearly 23 percent last year. Christianity's share of the country's population dropped from 78 percent to under 71 percent, according to Pew.
Millennial adolescents are less religious than baby boomers and members of Generation X were at the same age, according to Twenge.
"We also looked at younger ages than the previous studies," she said. "More of today's adolescents are abandoning religion before they reach adulthood, with an increasing number not raised with religion at all."
Twenge, SDSU's Ramya Sastry, Julie Exline and Joshua Grubbs of Case Western Reserve University and W. Keith Campbell of the University of Georgia poured over data from four national surveys of youth aged 13-18 taken between 1966 and last year.
According to the study, which was published in the journal PLOSOne, teens are less approving of religious organizations, are less spiritual and spend less time praying or meditating.
Compared to the late 1970s, twice as many 12th-graders and college students never attend religious services, and 75 percent more high school seniors say religion is "not important at all" in their lives, according to Twenge.
Compared to the early 1980s, twice as many high school seniors and three times as many college students in the 2010s answered "none" when asked their religion.
Compared to the 1990s, 20 percent fewer college students described themselves as above average in spirituality, suggesting that religion has not been replaced with spirituality, the researchers said.
"These trends are part of a larger cultural context, a context that is often missing in polls about religion," Twenge said. "One context is rising individualism in U.S. culture. Individualism puts the self first, which doesn't always fit well with the commitment to the institution and other people that religion often requires."
As Americans become more individualistic, it makes sense that fewer would commit to religion, she said.