Feb. 16, 2011— -- America is the most developed nation when it comes to religion. It has a dynamic, competitive religious marketplace -- which means it has winners and losers.

Watch "World News with Diane Sawyer" for more on this story tonight on ABC.

According to a report by the National Council of Churches, the biggest losers are the mainstream Protestant churches -- the Presbyterian Church, Methodists and Lutherans are all showing a dip in membership.

While each of them are down just a few percentage points (the data was compiled in 2009 and reported to the council in 2010) the declines have reached into the double digits over the last decade. Some of them are responding with ad campaigns.

"I think one of the things about mainline is that because it was the dominant church for so long, it took for granted that it would be publicly valuable," said Rev. Serene Jones of the Union Theological Seminary. "To suddenly find yourself no longer the big guy on the block, meaning you suddenly have to start figuring out who you are and explain yourself."

Pentecostal churches, on the other hand, are seeing a surge in membership. About 150,000 more people are attending the services this year, where members believe that the Holy Spirit can give you gifts, like speaking in tongues. Sarah Palin famously used to attend.

"It's a worldwide organization," said one man, a member of a Pentecostal church. "It is one of the fastest growing faiths in the nation today"

"It seems like one of the attractions to Pentecostalism, it's a full body faith," said a female member of the church. "It's a faith you can feel."

The Jehovah's Witnesses, known for their door-to-door preaching, had the largest growth of any single denomination. They believe secular society is corrupt, and that Armageddon is imminent. Famous members include Venus and Serena Williams. Membership shot up 4.37 percent in a year.

Membership in the Mormon Church also went up, by nearly 80,000 members. With famous members like Mitt Romney, Glenn Beck and "Twilight" author Stephanie Meyer, the church is doing more outreach to the mainstream media.

The biggest competition for churches isn't other churches, it's other things entirely, like television, the Internet and the mall. The new report says that total church membership in America continues to decline.

Fifteen percent of Americans say they have no religion, though that doesn't mean they've given up on God.

Religion in America: A New Survey

"They pray," said Jones. "They ask deep questions of life. And they are the ones I think in the long run are going to recreate religion in North America."

America's dynamic religious scene, perhaps in the midst of a new reformation.

Click here to return to the "World News" page.