HOUSTON -- A Saturday evening at the Second Baptist Church of Houston is like Christian worship in most American towns: a sermon, some music, nice people walking from the parking lot with Bibles in hand.

The difference is scale. Second Baptist is the second-largest "megachurch" in the U.S., a modern cathedral complex the size of an airport terminal. Inside "E Gym," where the congregation's "small" Saturday evening service is being held, two basketball courts full of believers in jeans and flip-flops rock out, sing along or just watch as a huge contemporary band jams to the song "Did You Feel the Mountains Tremble?"

White and yellow stage lights hit the rising smoke before the performance cools down for the opening prayer. The sermon stops for applause as the audience watches an video projected overhead of a Christian-gone-wild beach retreat, where the church baptized nearly 700 teenagers.

Spread across five campuses, Second Baptist has about 24,000 people attending one or another of its programs each week. The church has fitness centers, bookstores, information desks, a café, a K-12 school and free automotive repair service for single mothers. The annual budget: $53 million.

"We are a town within a city," says pastor Edwin Young, 73, whose sermon style ranges from conversational to yelling to Southerner-about-to-weep.

Churches across America--like shopping malls, houses, corporations, hospitals, schools and just about everything else--have erupted in size in the last few decades. The number of megachurches in the U.S. has leaped to more than 1,300 today--from just 50 in 1970.

Featuring huge stages, rock bands, jumbotron screens, buckets of tears and oodles of money, as well as the enormity of the facilities, pastor personalities and income--over $8.5 billion a year all told--these churches are impressive forces flourishing at staggering rates.

On a megachurch database updated by the Hartford Institute for Religion Research at Hartford Seminary in Connecticut, Second Baptist in Houston is listed as the second-largest based on average weekly attendance. (No. 1 is Lakewood Church, five miles from Second Baptist. And rounding out the top 10 are North Point Community Church, near Atlanta; Willow Creek Community Church, near Chicago; LifeChurch.tv, of Edmond, Okla.; West Angeles Church of God in Christ, Los Angeles; Fellowship Church, of Grapevine, Texas; Saddleback Valley Community Church of Lake Forest, Calif.; Calvary Chapel, of Ft. Lauderdale; and The Potter's House, of Dallas.)

Second Baptist's "21st Century Worship Center" is being refurbished since Hurricane Ike hit last year. Originally built in 1986 for $34 million, the church is spending $8 million for repairs and upgrades, not including what insurance covered. An electronic projection system will display scripture verses around the cavernous, octagonal, balconied room, which will seat about 6,500 people under a dome that reaches six stories high. There are towering columns and larger-than-life faceted glass windows depicting the Biblical stories of the beginning and ending of mankind.

"You won't find anything in here that is ostentatious. You'll find beauty," says Pastor Young. "God's house ought to be beautiful." Young, a self-described "redneck, blue collar, south Mississippi country boy" and son of a utility-pole-lineman, started his flock in 1978 with 300 attendees--less than half the number of teenagers baptized at the beach recently.

"It's a phenomenon of this generation," he says of the sheer size and growth of congregations like his. "It's meeting some niche there."

Megachurches, considered Protestant, with more than 2,000 people attending each week, cut a wide swath across the country. In 2005, California led the nation with 178 of them, followed by 157 in Texas and 85 in Florida, according to the book Beyond Megachurch Myths: What We Can Learn From America's Largest Churches.

"We believe it is only a matter of time until every state has a congregation of megachurch size," write authors Scott Thumma and Dave Travis. "Americans have not only grown accustomed to large organizations, but they have even had their character and tastes shaped by them."

Thumma, a professor at Hartford Seminary, has since his book reported that the average megachurch income was $6.5 million in 2007, up from $4.7 million in 1999. About 50% of it was spent on salaries, the rest divided evenly between missions and buildings. Meanwhile, he says nine out of 10 megachurches more than doubled in size between 2002 and 2007.

Among the fears of Ed Young Jr., pastor of Fellowship Church in the Dallas area, No. 7 on the list of largest megachurches, and gaining on his father at Second Baptist, is the financial accounting of growth that comes with mergers and added campuses. And he wonders if megachurches are "just taking people from other churches because we have a cooler church."

Only 6% of megachurch attendees who participated in one of Thumma's surveys said they were at their first church. They appear to be being pulled from other congregations or brought back into practicing their faith after falling off the wagon. Two-thirds of megachurch attendees have been going for five years or less, he found.

A third of megachurch attendants are single compared with 10% at a typical church, and the average age is 40 compared with 53. Twenty-six percent of families at megachurches earn more than $100,000 a year, compared with 15% at typical churches, which tend to have slightly better regular attendance rates.

But questions over tax-exemption status and squabbling over high-profile pastors are growing concerns. In recent years, none more than Joel Osteen, 46, the best-selling author and pastor of Lakewood Church in Houston, the largest megachurch in the country, has been questioned more about his riches.

"God has blessed me with more money than I could imagine from my books," says Osteen, who gave up his $200,000 salary about five years ago, when royalties started flowing from his Your Best Life Now. He adds of he and his wife, Victoria: "I don't think it has changed our lifestyle, it has just given us the opportunity to help more people."

Joel's father started Lakewood with a congregation that would fit aboard two buses and grew it to 6,000. Since he died in 1999, Joel has grown the flock more than seven fold. In 2008 Lakewood had a $70 million budget, up from $50 million in 2005. In addition to the 7 million watching on television in the U.S. (services are broadcast to more than 100 countries), about 43,500 people come to the former Compaq Center, where the Houston Rockets used to play, for any of the five weekly services.

Lakewood leased the center from the city of Houston in 2004 for 60 years, paying $13 million in cash for the first 30 years rent. Then they threw $95 million more in on top of that to try to make the 650,000 square foot building feel like an intimate church. There is wall-to-wall carpet beneath the 14,000 seats. The largest of three jumbotron screens is 32 feet by 18 feet. Twin waterfalls book-end a stage that rises and falls before a circling gold globe and a pulpit, where Osteen, often lambasted by critics for being light on theology, preaches about staying positive. He says he doesn't want to be "too religious" in hopes to reach the "everyday person."

"Don't drive up and down the freeway and just see the traffic, potholes and the construction. Look out at the beauty of God's creation. Look out at the trees, look up into the sky. Breathe in the goodness of God," he told his following on a recent Sunday. "When that critical spirit comes, you have to deal with it one thought at a time."

Out in the sea of believers and donators, amid scores of television cameras, was James Lyster, 38, a tattooed steelworker dressed in a suit. Others came in jeans and T-shirts. "The spirit of the Lord is here," he says. So is the rumble of a dramatic drum solo and the blare from a band belting the lyrics of "Come in From the Outside Just as You Are."

After the service, some 400 people lined up to visit with the Osteens. An usher had to cut it off. "I've already turned away 100 people," he said. Nearby was a man who said he visited from Idaho with his son who was about to be treated locally for leukemia. Another, A. D. Achilefu, 28, whose father is from Nigeria and has attended Lakewood for eight years, says the congregation is a good glimpse of what heaven will be like: "a big melting pot."

"Osteen is responding to the psychological needs of our culture in a theologically accessible way," says Nathan Carlin, a doctoral student in religion studies at Rice University, who co-authored the recent article in Pastoral Psychology "Joel Osteen as Cultural Selfobject."

"Many preachers tell us that God loves us, but Osteen makes us believe that God loves us. And this is why he is so successful," he says.

It's unclear how much more successful he can be or how much bigger megachurches can get, even in Texas. One sign of success: Despite the economic downturn, Lakewood says they are on par with last year's collections.

"When I was growing up, a church of 1,000 was a big deal," Osteen says. "But you know what, it's just a different day today. I don't know where we will be in 30 years. Will there be churches of 100,000 or will we be meeting in big stadiums? I can't fathom that now, but I don't know." It could come sooner than that. In April 45,000 people filled New York's new Yankee Stadium to hear him speak.