By Dan Merica, CNN

Washington (CNN) – The percentage of Americans 30 and younger who harbor some doubts about God’s existence appears to be growing quickly, according to a recent Pew Research Center survey. While most young Americans, 68%, told Pew they never doubt God’s existence, that’s a 15-point drop in just five years.

In 2007, 83% of American millennials said they never doubted God’s existence.

More young people are expressing doubts about God now than at any time since Pew started asking the question a decade ago. Thirty-one percent disagreed with the statement “I never doubt the existence of God,” double the number who disagreed with it in 2007.

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When asked about doubts of God, no other generation showed a change of more than 2% in the past five years.

The survey found that the percentage of millennials who identify with a religion is remaining constant, while most other generations have seen religious identification increase in the past 10 years.

The findings about millennials and religion were part of a 168-page report that Pew released June 4 but were largely overlooked.

“Notably, people younger than 30 are substantially less likely than older people to say prayer is an important part of their lives,” the report said.

“Research on generational patterns shows that this is not merely a lifecycle effect,” it continued. “The Millennial generation is far less religious than were other preceding generations when they were the same age years ago.”

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The findings are part of Pew’s 2012 American Values Survey, which touches on issues including political partisanship, gay marriage and abortion.

Despite the findings on millennials, the survey shows that the United States continues to be a highly religious nation, with most Americans identifying with a particular faith.

Seventy-six percent of all respondents said prayer is an important part of their lives and agreed that “we all will be called before god at the Judgment Day to answer for our sins.” About 80% said they have never doubted the existence of God.

The report points to a growing divide between the youngest and oldest Americans on belief, religion and social issues.

According to Jesse Galef, communications director for the Secular Student Alliance, the growth in “doubting” youths has led to a surge in secular student groups.

“For a lot of millennial atheists, they are expecting to find a group, they are coming to campus, and if they don’t find one, they are starting one,” Galef said. “This is completely different than what other generations grew up with.”

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The Secular Student Alliance has affiliates on 357 American campuses, Galef said, up from 81 such affiliates in 2007.

Galef says the Internet has created a place for young people to discuss religious doubts.

“It enables anybody to have open discussions without fearing if their parents would find out or what their communities would say,” he said. "The more safe places we create for young people to discuss their doubts, the more they can inspire questions in others."