"Church membership has never been higher," Stark says. "People like to think that in Pilgrim days, everybody lived in church — but hardly anybody went to church in colonial America because hardly anybody went to church in Europe. Somewhere around 1776, 16 percent belonged to church, now it's about 70 (percent)."
Religious marketplace vs. religious 'ecosphere'
America's religious landscape could easily be called a marketplace. There is competition, success and failure and there are many choices, but David Campbell, co-author of "American Grace: How religion Divides and Unites Us," says the undulations in American theology are more organic.
"In a biological world, you find lots of different niches," Campbell says from his office at the University of Notre Dame. "Depending on your own preferences and beliefs, you will find a religion in America to match what you are looking for."
The reasons people leave their church, even if it's the church they were raised in, vary from losing a belief in God or the church's teachings to disliking the practice and people at their church.
People are most likely to change their religion based on what their friends and family are doing. The most successful churches in America keep that in mind as they proselytize.
"I can move into a neighborhood and after a year being there, I can tell you what churches are growing and what ones aren't," Stark says. "The ones that are growing will have contacted me, and the others that aren't will not."
Successful churches also hold true to their core teachings, but they innovate "everywhere else," Finke says. Megachurches, like Joel Osteen's Lakewood Church in Houston, which draws an average weekly attendance of about 40,000 people and broadcasts a weekly live sermon on television, innovate in the way they include music, organize socially or incorporate social media. LifeChurch.tv, based in Edmond, Okla., reaches almost 30,000 people weekly through transmissions to satellite locations and through the Internet.
In one upstart church in Seattle, Stark says, the congregation grew exponentially over the course of a decade because of the way they marketed their church activities. For a Saturday night sermon, the giant billboard outside the church said, "Take her to church, and then to dinner." Bible camp advertised horseback riding, reading and Karate.
For the Hansens, the Episcopalian church across town appealed to them most through its balance between teaching and worship. You'll find them there on Sunday mornings; happy, holding leadership positions and teaching Sunday School. They don't plan on going anywhere else any time soon, but if they had to, they know they've got options.
"I don't know that we felt liberated (affiliating with a different church)," Hansen says. "But we knew there were enough choices out there that worrying about where we might end up didn't keep us from trying to do the right thing where we were."