The Jonas Brothers interview: Faith, pop and chastity

IT'S EARLY afternoon and a fitful drizzle is falling on a small but steadily growing throng of teenage girls outside a London hotel, lollipops in their cheeks and boy bands on their minds. They have skipped school to wait for "the best band in the world, except maybe JLS and Mcfly" to come out of the hotel, get into their limo and drive off to the premiere of their new film.

After a tantalising glimpse, the plan is to sprint to Leicester Square to join the hundreds of other girls fainting, weeping and screaming at the sight of three good Christian boys from New Jersey who cultivate the most cherubic curls in rock, wear purity rings that pledge virginity until marriage, and make the most wholesome music since The Osmonds implored us to love them for a reason. They go by the names of Nick, Joe and Kevin Jonas, or the Jonas Brothers. Like Beatlemania, the fanatic response to them even has a name: OJD, or Obsessive Jonas Disorder.

Inside the hotel, the boys, 16, 19, and 21 respectively, are promoting their new film, The 3D Concert Experience, a kind of Hard Day's Night for the Disney Channel generation. In the flesh, objectively speaking, it has to be said the Jonases are adorable: fresh faces framed by halos of brown hair, buffed and coiffed, extremely well-mannered for rock gods. "We're pretty easy-going guys," says Kevin. "Nothing really gets on our nerves." And this in response to a question about their worst flaws.

Filmed during their Burning Up tour of last year that drew more than a million fans, The 3D Concert Experience opens like the Beatles film with the band chased by hysterical girls. Think of it as the anti-In Bed With Madonna. There may be the same mix of live performance and backstage footage but we're talking rocking out on skinny-jeaned knees and early nights rather than conical bras and bottle fellating.

Sex, drugs, cursing and presumably all foolish teenage behaviour have no part to play. Take what they say about going through adolescence with the Disney publicity machine forever whirring behind them. "It's not difficult," says Kevin. "We see all this as an opportunity to be who we are. We're not perfect, we never said we were. We're just trying to live every day and make mom proud." The other two nod, expert at presenting a united front whenever a Jonas speaks. It's impossible to find a chink in their Disney armour. The Jonas Brothers make Hanson, the Mmmmbop band of brothers in the 90s, look like The Sex Pistols. I almost squeal in delight when Kevin drinks a cappuccino. Aha, caffeine! A vice!

"Occasionally you have to be aware of things," says Joe, the heart-throb and most shy Jonas, who bizarrely metamorphoses into a Disney version of Mick Jagger on stage. "But you don't let it change you. You are who you are and you don't want all this to take a hold of you. Just be yourself and be careful." More nods. Nick, the youngest, who is known as Mr President because he writes the songs (he also appears to be the most musically talented, playing guitar, drums, and piano), pipes up: "I think you do feel a certain sense of responsibility, but that's good. It's important to have that feeling. It's healthy for your growth." A suggestive Vanity Fair shoot, la Miley Cyrus, or a Britney Spears meltdown after her similarly innocent Mickey Mouse Club beginnings don't seem due any time soon.

It might seem easy to explain the Jonas Brothers phenomenon as uniquely American: raised by a pastor with a penchant for Christian rock, performing on Broadway before they entered double figures, powered by the terrifying self-confidence that seems the right of every Disney fledgling. But the world has gone mad for the Jonas Brothers. The London girls outside the hotel I speak to say they love the band because they are saving themselves for marriage. In a pop industry saturated by sex and drugs, the Jonas Brothers have tapped into the opposite, offering traditional values, earnest white rock, and the chance to get sprayed with "harmless" foam during their concerts. Unbelievably, and not just in America, they have made chastity cool.

They often refuse to discuss their purity rings and avoid describing themselves as a Christian band. Are they sick of being questioned about it? "Faith is a big part of everything we do and we were raised in the church," says Nick. "But as a band that's not our main focus," adds Kevin.

No matter the naysayers who claim religion and rock'n'roll don't mix, the Jonas Brothers are the next Disney fairytale story of global domination, following on from Hannah Montana and High School Musical.

"We were in Spain recently doing a meet and greet and it got very crowded and they had to pull us out," says Kevin. "They thought we'd get 5,000 but 25,000 showed up. It was intense, a little scary at times but exciting." Don't they ever tire of the sound of screaming girls? "I think we know our fans have a very unique way of showing their appreciation for our art," says Nick. "It's amazing to be able to do what we do and we're so thankful to them for making it all possible." They talk so often of their love for their fans I start to wonder if it's written into their contracts that they have to mention them in every third sentence.

Occasionally, though, the attention can get creepy. "The other day we had a show in the Bahamas," Nick says. "I was alone in the dressing room and this mother and daughter just walked right in, came up to me and were like, 'We love you'. She had a pass and looked like she knew what she was doing. Suddenly, all this security showed up."

It has all happened at lightning speed. In the past two years the Jonas Brothers have become platinum-selling artists the world over, played to millions, been Grammy nominated, and last year were the first artists in history to hold three top ten spots in the Billboard charts at the same time. When they made the cover of Rolling Stone in 2008, it was the magazine's biggest selling issue of the year.

It all started with Nick, who was discovered singing in a barber shop in New Jersey while his mother had her hair done. He, like his brothers, learnt to play music in the church where his father delivered the weekly sermon. After appearing on Broadway, he won a deal with Columbia Records in 2004 and released an album of spiritual songs. Not long after, the brothers were pulled on board. "Things weren't really working as well as we hoped," admits Nick. "We'd be playing to seven people in New Jersey every night and then doing a school assembly in the morning that meant loading in the van at 6am. That went on for a year."

Columbia let them go in the end without releasing their second album. It didn't take Disney long to snap them up, and introduce them to their target audience with a spot on the Hannah Montana TV show. Their father gave up being a pastor to manage them full time, and the albums, tours, TV, films and megabucks have followed. There is even another brother in the wings, Frankie, who has started a band and is currently promoting a film. He is eight years old.

Did they ever think about jacking it in during those years playing to empty venues? Of course they didn't. "We saw the potential," says Joe. "The seven people who were there were pumped."

"There were times when it was scary," says Kevin, and his fellow Jonases nod solemnly. "But we all had this dream and knew what we wanted to do."

• Jonas Brothers: The 3D Concert Experience is released 29 May www.disney.go.com/disneypictures/jonasbrothers3d/