They're uninterested in trying to talk a diverse set of friends into a shared viewpoint in a culture that celebrates an idea that all truths are equally valid, he says. Personal experience, personal authority matter most. Hence scripture and tradition are quaint, irrelevant, artifacts. Instead of followers of Jesus, they're followers of 5,000 unseen "friends" on Facebook or Twitter.
"I think Jesus is getting lost in the data stream," says Kinnaman, president of the Christian research firm The Barna Group.
"'Spiritual' is the hipster way of saying they're concerned with social injustice. But if you strip away the hipster factor," says Kinnaman, "I'd estimate seven in 10 young adults would say they don't see much influence of God or religion in their lives at all."
This trend may have been leaving subtle tracks for years.
The hot religion statistical trend of recent decades was the rise of the "Nones" — the people who checked "no religious identity" on the American Religious Identification Surveys (ARIS). The Nones numbers leapt from 8 percent in 1990 to 15 percent in 2008.
The So Whats appear to be a growing secular subset. The Pew Forum on Religion & Public Life's Landscape Survey dug in to the Nones to discover that nearly half said they believed "nothing in particular."
Neither raging atheist scientist Richard Dawkins, author of numerous best-sellers such as "The God Delusion," nor televangelist Pat Robertson would understand this fuzzy stance, says Barry Kosmin, co-author of the ARIS and director Institute for the Study of Secularism at Trinity College, Hartford, Conn.
"But a lot of these people are concerned more with the tangible, the real stuff like mortgages or their favorite football team or the everyday world," Kosmin says.
The Rev. Ema Drouillard, who specializes in San Francisco-area non-denominational ceremonies, said in 2001 about 30 percent of her clients refused any reference to religion at their weddings.
A decade later, 80 percent of her clients choose her carefully God-free ceremony. The only faith they pledge is in each other. No higher authority is consulted as they vow to walk beside each other, "offering courage and hope through all your endeavors."
"A lot of people just aren't on any spiritual path. They say, 'We are just focusing on the party.' Or they have no language for their spirituality so they just leave it out," Drouillard says.
When church historian Diana Butler Bass researched her upcoming book, "Christianity After Religion: The End of Church and the Birth of a New Spiritual Awakening," she found the So Whats are "a growing category."
Says Bass, "We can't underestimate the power of the collapse of institutional religion in the first 10 years of this century. It's freed so many people to say they don't really care. They don't miss rituals or traditions they may never have had anyway."
For them, the Almighty is off the radar, like some tiny foreign country they know exists but never think about.
"God? Purpose? You don't need an opinion on those things to function," says Suhas Sreedhar, 26, a engineer working in a computer company in Manhattan.
Raised in New Jersey by his devoutly Hindu mother and staunchly atheist father, "I was saturated with both views and after a while, I realized I don't need either perspective.
"There may be unanswerable questions that could be cool or fascinating. Speculating on them is a fun parlor game, but they don't shed any meaning on my life," Sreedhar says.
This is a disaster for Christians, says Scott McConnell, director of LifeWay Research,
"If you're not worried about heaven, you won't notice or care if Jesus is essential your salvation. You're not thinking about any consequences," McConnell says.
But Rabbi Micah Greenstein of Temple Israel, Memphis, is not so alarmed. He sees people behaving spiritually — caring for each other and the world — even if they skip the label.