When it comes to denominations, Cox added that "'brand loyalty' is a thing of the past."

Religion an Individual Pursuit?
What's going on? George Barna thinks many people are looking for an authenticity, passion and sense of community they find lacking in many churches.

"Americans remain unconvinced of the necessity of the collective faith experience," he said. "This is partially because the typical church model esteems attendance rather than interaction and immersion, partially due to the superficial experiences most believers have had in cell groups or Christian education classes, and partially attributable to our cultural bias toward independence and fluid relationships."

But is a Lone-Ranger pursuit of spirituality the answer? Many church leaders see a danger in this approach. In 1983, well before he became Pope Benedict XVI, Cardinal Joseph Ratzinger, Prefect for the Congregation for the Doctrine of the Faith, addressed "the relation between personal experience and the common faith of the Church."

He wrote: "Both factors are important: a dogmatic faith unsupported by personal experience remains empty; mere personal experience unrelated to the faith of the Church remains blind."

In other words, for Christianity, at least, the Christian life must be lived out in the context of the community of believers. Barna states emphatically that "the Bible is unambiguous about the importance of experiencing God through a shared faith journey, and Jesus' example leaves no room for doubt about the significance of involvement in a faith community ...."

Although he seems to applaud the individualistic spirit growing in America's religious communities, Cox also sees potential dangers lurking behind the trend. "Religions without unassailable leaders and with hungry competitors may find themselves marketing as much as ministering," he said. "Meeting buyer preferences may seem essential in business, but it can eviscerate the integrity of the religious 'product.' Imagine what the Ten Commandments or the Sermon on the Mount might have been if Moses or Christ had poll-tested them."

Challenges for the Church
It's not all bad news. Barna said a significant number of people appear to be leaving the organized church flock, but not for pagan or otherwise non-Christian religious pastures. Instead, they appear to be opting for a more informal pursuit of the Christian life through home churches.

In the last decade, according to Barna, the percentage of adults who attend a house church during a typical week grew from just 1% to 9%. If monthly attendance is considered, Barna said "one out of five adults attends a house church at least once a month."

Where do those who identify themselves as Christian go to experience their religious faith traditions? According to a 2006 Barna Group report:

74% attend only a conventional church
19% attend both a house church and a conventional church
5% attend only a house church
2% small group, but not considered a house church