The number of Americans who call themselves Christian has fallen 10 percent over the past two decades --from 86.2 percent in 1990 to 76 percent last year.
For American Jews, there's been a drop from 1.8 percent to 1.2 percent over the same period.
Researchers questioned more than 54,000 American adults about their beliefs and practices for the American Religious Identification Survey, using the same methodology they used in 1990 and 2001 surveys.
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Duke Divinity School professor Mark Chaves, who studies such trends, points to changing demographics.
"Increasing divorce rates, fewer people marrying, getting married later, means that more and more kids are raised in households that aren't religious," he said. "The biggest predictor of having a religious identity as an adult is having had one as a child."
Michelle Pickett of Raleigh is a good example of that. Pushing her two year old daughter, Emma, in a Pullen Park swing, she says passing on the family's religious traditions has been essential.
"Both my children will be raised Catholic, in the Catholic community," she said. "We go to St. Francis of Assisi off Leesville Road, and I just feel like with the strong faith and belief that we have it is important to instill in our children my religious background."
Another interesting note in the survey is the increasing number of "nones" --"none" as in "none of the above," when it comes to choosing a faith.
From 1990 to 2008, the percentage of Americans stating no religious preference nearly doubled to 15 percent.
In fact, the number of Americans claiming no religion at all now outranks every other major US religious group, with the exception of Catholics and Baptists.
Nearly three million Americans are now aligning themselves with other religious movements, such as New Age and Wicca. And the number of self-declared Muslims has doubled over the last two decades from .3 to .6 percent.
Bishop Michael Curry of North Carolina's Episcopal Diocese says America is going through a cultural change.
"I would argue that people are more profoundly religious and expressing it, but it's coming out in new ways," he said. "You hear it in language about 'spirituality.' You may not hear it as consistently in terms of institutional religion, but the spiritual quest (is there), the hunger."
To feed that hunger, the Episcopal Diocese has launched a new ad campaign to help attract worshippers, particularly younger ones.
Duke's Professor Chaves says the numbers should be kept in context.
"It doesn't mean that there are fewer people attending religious services, going to church," he said. "Religious attendance is only slightly down or stable over the same period of time. What's happening is that more people who were probably already religiously inactive but still says, 'I'm Catholic, or I'm Baptist, or I'm Methodist, more of those people are now say 'I'm nothing'."
At Durham's New Hope Church, there's no shortage of enthusiastic worshippers.
In seven years, the congregation has grown from just the pastor's immediate family to more than 1,500 who come for Sunday services. With its Christian rock music and stage lights, New Hope's style is non-traditional to say the least.
Pastor Benji Kelley, who dresses in casual clothes when preaching, makes no apologies for it.
"They're voting with their feet," he says. "They're leaving the church because they show up and the church doesn't sound like the music they listen to, the message is not relevant, and it just has no place in (their) life. And what we've done is, try to say, no-no-no, Christianity is always relevant."
Kelley says the Church's message doesn't change, even if the way it's delivered does.
"I really believe that one of the greatest mistakes, or should I say sins in all the world is to take the most exciting news ever heard the gospel of Jesus Christ and bore people to death with it," he said.
