Jesus Inc. Welcome to the world's biggest church

"We know that God has good things in store for you. How many of you are ready to worship the Lord?" asks the young, besuited pastor, Joel Osteen, who takes to the stage with his wife, Victoria. The mighty roar of noise from the people indicates that we all are.

If religion is a numbers game, it may be that the Lakewood Church in Houston, Texas, has it all wrapped up. Amid the recent growth in the US of so-called "mega-churches" this non-denominational church, which started life in 1959 in a feed store, was recently listed as having the biggest congregation in the country. Every Sunday it draws around 30,000 people to the two morning services, in addition to a lunchtime Spanish-language service of 8,000 worshippers and a Wednesday evening service attended by around 10,000.

The numbers have got so big that last month the church moved premises and took up home in a stadium that previously hosted the Houston Rockets basketball team. The seats that were once full of sports fanatics are now filled with a different kind of worshipper; the choir and band sit directly behind where one of the hoops used to be. The church spent $95m to lease and refurbish the stadium, which now features two waterfalls. They spent $20m on the air-conditioning system alone.

The buzz surrounding Lakewood has been growing for the past 18 months, since the church announced that it wanted to take over the stadium in central Houston. As the date for the planned move approached, doubts were raised. Some suggested that the congregation would not want to travel across the city to the new location. As it was, on that first Sunday there were so many people trying to get to church that some were stuck in traffic jams for two hours as they tried to park. The faithful, typically enough, said it was a miracle.

What may be miraculous is the speed with which Lakewood has grown, and the reach of its message. Those unable to attend the services in person can watch live on TV in more than 35 cities across the US and on broadcasts that reach 100 countries. The services are streamed live on the internet. In addition, Osteen's book Your Best Life Now: 7 Steps to Living at Your Full Potential has been in the New York Times bestseller list since its publication last October and has sold around three million copies.

But what is it about Lakewood Church and its 43-year-old pastor, who began preaching only six years ago, that draws them in? Is it the music, is it the lights, is it the message that Osteen delivers? Does it have something to do with being among all those people?

It's some time before 8am on the third Sunday of Lakewood's existence at its new home. Already the streets are full of police officers and volunteers in orange jackets directing the cars to a series of car parks, while churchgoers who have already parked are heading on foot to the stadium. There are minibus shuttles for those who don't want to walk in the steamy high-summer temperatures.

The people who attend Lakewood are white, black, Hispanic and Asian. They are young and old, there are entire families, couples and singles. There are people dressed in the sharpest suits and there are others in chinos or shorts. Most are carrying bibles.

At the doors to the stadium are a team of "greeters" wearing name badges. "Welcome. Thank you for coming this morning," says Regina Blancas. She is a dispatcher for a school district's bus service. As a teenager she used to come to the stadium to watch the basketball and to see bands such as The Go-Gos. She and her husband had seen Lakewood on TV and decided to give it a try: they've been coming ever since.

"I like the positive words and I like that Joel preaches from the bible and talks about everyday things that matter," she says, "things that we need to get through the week."

Inside the stadium, the seats are already filling up. The 8.30am service is not as busy as the 11am but there are still a lot of people here and there's a buzz of anticipation - not dissimilar to that before a rock concert or a large sports event. The people appear so happy, so friendly. There are volunteers to find you a seat, people who vigorously pump your hand, people whose vigour increases when they learn you are a visitor. Welcome to Lakewood they say.

Soon the band and the choir are in full flight and a blonde singer, something of a Celine Dion lookalike called Cindy Cruse-Ratcliff, is on the stage in a peasant skirt leading the congregation in a series of rousing gospel-rock numbers. The band is fabulous and the tunes are annoyingly hard to forget but the words - flashed on to three huge video screens - don't quite seem to cut it. The lyrics to one number go: "Higher than the heavens, stronger than the sea, mightier than the mountains, your love amazes me." If you didn't know better you might think Cruse-Ratcliff was singing about her boyfriend.

After four or five numbers Osteen and his wife appear on the stage. He looks incredibly young. His hair is gelled back, his suit appears to glisten and his smile is the whitest shade of white. Victoria wears a Chanel jacket and has large Texan hair. They look like a successful young couple who have just taken charge of their own car showroom.

But of course Osteen is a salesman of sorts and it immediately become clear he is really quite brilliant with his pitch. And his pitch is motivation and positive thinking. Don't worry about the bad things in your life, focus on the good. Don't be negative, be positive. Precondition your mind to have a good day. Precondition your mind to be successful.

A typical Osteen line goes something like this: "I know a man who this week had to go in hospital for open heart surgery. And I was talking with some other of his friends and they said how bad it was that he had to go into hospital. And I said, well I sort of know what you mean. But I turned it around. I said let's be thankful that there are good doctors and good hospitals and that he can be corrected."

In response to this glass-half-full rhetoric the congregation roars and cheers. It seems everyone is clapping, some say "Praise Jesus" and other such declarations.

And so it goes. If you lose your job, think of the new opportunities God has opened up for you. If you're diagnosed with cancer don't be down, but remain positive. If you get stuck in a traffic jam or miss your plane, don't get angry but simply remember God has a reason for everything and remain optimistic that the reason will become clear to you. Osteen says: "You can't go around having negative thoughts if you want to have a positive life." But what there is very little of during the 90-minute service is any real talk of God or of Jesus or, indeed, how Jesus might like us to behave. There is an awful lot of talk about being positive, about preconditioning our minds, but very little talk about what we might do with our positivism or success. At one point, Victoria, who also preaches, says, "God wants you to be financially successful [because] you are his representatives on earth." So much for the rich man and the camel and that business about the eye of the needle.

At some point during all of this the idea strikes you that just maybe you have wandered into the wrong building and actually you're listening to a motivational speaker delivering a presentation for company executives, while the church service is taking place next door. The teachings of Christ? Oh, we'll deal with all of that on a PowerPoint later.

Likewise, there's no mention of any of the other controversial topics that have been rallying points for some Christians. There is no talk of gay marriage or, indeed, homosexuality. There is no mention of abortion or stem-cell research. The closest it gets is when Osteen says the church runs classes to help people overcome addictions - "sexual addictions, other addictions". He seems to hurry the words.

Osteen has certainly been accused of preaching a form of "Christianity-lite". Michael Horton, a professor at Westminster Theological Seminary near Philadelphia, said of Osteen: "God is not the centre of his theology. The centre is me and my happiness." Publishers Weekly, meanwhile, described his bestselling book as a "treatise on how to get God to serve the demands of self-centered individuals".

In person, Osteen is pleasant, likeable and seemingly very genuine. He does not claim to be something he is not. In fact, he seems somewhat surprised by the soaring success of his church when all he had ever wanted to was to maintain the - admittedly large - congregation of 5,000 that his father preached to. He denies the allegation of being lightweight but admits that he wants people to feel upbeat.

"It's positive, it's hopeful. You hope people leave feeling better than when they came in," he says, sitting in a lounge deep beneath the stadium. "It's victorious. You can feel it."

Serious issues - the ability to forgive, the willingness to move on - are discussed, he says, but there is no reason why his message needs to be complicated. "Jesus used to tell simple stories, he talked in parables. He was not always deeply theological," he adds. "When they say we're light, all they have to do is come one week and attend a service. We talk about forgiveness and deal with all those issues."

Osteen, who has no formal theological training and learnt from assisting his father for 17 years before his death in 1999, is very much focused on the future. He wants to build the church and spread the message. It is a business plan. He believes that one day his congregation could reach 100,000. Everything that is healthy, he says, is growing.

"A lot of churches have not moved with the times," he adds. "If Jesus were here today he wouldn't be riding around on a donkey. He'd be taking a plane, he'd be using the media."

The size of the congregation is a positive thing for those who come to worship, he says and the design of the stadium adds to the experience. "I like the fact that it's designed so that everybody can see each other."

Christianity-lite or otherwise, Osteen's brand of pile-it-high, aspirational preaching is working. He admits that while their focus is on attracting people who currently do not attend a church, the success of Lakewood is taking place at a cost to other, smaller churches that are losing numbers.

One such Lakewood member is Ted Dealing, who started coming to hear Osteen two years ago. Previously he had gone to another church and considered himself a Christian but realises now that he was "not saved". "There has been such a difference in my life," says Dealing, who like many others had first seen Lakewood on television. "It is a positive, uplifting church. Some others have called it Christianity-lite but it's not light at all." Another member of the congregation, Chuck Gluch, is attending with this wife, Carol. Like others he claims Osteen provided useful, practical insights into life that had an everyday relevance. But he admits: "If I was a theologian I would probably have a problem with Joel and I'd definitely have called it light, but what Joel does is take an everyday situation and he gives me a way to work with it."

After the services there is always a sizeable queue that lines up at the rear of the stadium to shake hands with Osteen and his wife. People ask for autographs and for photographs, for a private word or simply for a quick handshake. The couple are not quite treated like rock stars but they are certainly celebrities. Both are unfailingly charming and obliging, the bright-white smiles never absent.

But while some people linger after the services, most appear to head for the doors and thence to their cars. They wait with their bibles for the shuttle buses or else walk to the car parks, ready to face the week ahead, ready to come back again in seven days. People stream from the main exits, they stream out of the side doors and from the underground entrance. There are an awful lot of people.