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What's the biggest religion in America: Catholicism? Evangelical Christianity? Mainstream Protestantism?

It's consumerism, according to the Rev. Billy -- the deeply held American belief that buying stuff makes us better and happier, that purchases can fill the voids in our hearts and souls.

"We really do consider it (consumerism) the largest fundamentalist religion in America today," the Rev. Billy said. "It makes us stand in lines, sit in traffic and tells us we need 23 different products just to take each other on a date."

If you're aware of the Rev. Billy, it may be from the 2007 documentary about his performance art/ministry, "What Would Jesus Buy?" Or his run as a "protest candidate" for mayor of New York in 2009.

Or maybe you have heard about the comedic exorcisms he and his gospel-choir group -- once called the Church of Stop Shopping, now the Church of Earthalujah -- performed in bank lobbies, Disney stores, Wal-Mart headquarters and the Tate Modern museum in London, where British Petroleum funds a gallery.

The targets: big business, big oil companies and big banks, which the Rev. Billy and his crew say promote consumerism and a laundry list of economic and environmental ills.

The Rev. Billy is the creation of Bill Talen, the son of a Midwestern banker and a refugee from the harsh Calvinist religion of his youth. Talen was an actor and writer in San Francisco before moving to New York City in the mid-1990s. That's where he created the Rev. Billy as a parody of pompadour-styled televangelists and where he soon gathered a choir of like-minded activists. Using humor, hallelujahs and the vocal hallmarks of evangelical ministers, the Rev. Billy preached the evils of consumerism and related ills: sweatshop labor, environmental degradation and big chains that muscled out family-run businesses.

Liz Weston

Liz Weston

He was coached by a mentor, the Rev. Sidney Lanier, the vicar of an Episcopal church that served New York's theater community. Lanier encouraged Talen to study how televangelists delivered their messages -- the cadence and rhythm that captured their audiences.

"It's an awesome vocal form . . . when you turn off the content," Talen said.

What started as protest art, though, has morphed since the 9/11 attacks. Talen, who spoke to me while on a break from leading workshops on "Art and Dissent" for the Hemispheric Institute in Chiapas, Mexico, said people started turning to his group for comfort and a spiritual connection after the World Trade Center towers fell.

"They trusted us as a way to be together to reflect about life without a fundamentalist, judging God," said Talen, who officiates at weddings and baptisms in his role as a minister. "We started developing a fellowship, a way to pray together, to sing together."

And they perform. A weekly show in Manhattan's East Village is scheduled to continue this fall after the Rev. Billy and his choir return from their tours of Europe and Mexico. The shows, along with their public protests staged as "interventions" and "exorcisms," use humor and original songs to question mindless consumerism.

"We use the drama of a joyous gospel choir and a televangelist to interrupt and change Americans' relationship to consumer products," Talen said. "This consumer economy has endangered us. We need to make basic changes."

Talen believes some of those changes are already under way, because of the staggering economy. With more people unemployed and underemployed, families are spending more time together rather than shopping for things they don't need. People are starting up businesses, and Americans are more aware of the importance of supporting local businesses.

Talen thinks we're capable of changing even more, of creating a kind of sustainable consumerism that doesn't create economic or environmental catastrophes. Falling into the cadence of a preacher, he references America's past: "We made a revolution. We abolished slavery. We marched for civil rights. We can do this."

But Talen worries the changes aren't happening fast enough to save us -- or our planet. That's why he's not particularly concerned that some people take offense at what he's doing and how he's doing it.

"We have to spend a little less time worrying about other people's feelings," Talen said. "New ways of believing always hurt the feelings of the people who believe the old way."

That said, he doesn't want his message to become too dogmatic or inflexible. He still likes to laugh and to make others laugh.

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"I don't want to become a fundamentalist myself," Talen said. "We're all doing what we can. We need to forgive each other and move on."

Liz Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "The 10 Commandments of Money: Survive and Thrive in the New Economy" (find it on Bing). Weston's award-winning columns appear every Monday and Thursday, exclusively on MSN Money. Join the conversation and send in your financial questions on Liz Weston's Facebook fan page.