In many they are without either clothes or dignity. In the way that we have difficulty picturing our parents 'doing it', the ostensibly crude sexual content seems at odds with the persona of the artist and certainly troubles some viewers. They've always been controversial; Mary Whitehouse got plenty of mileage out of them in her day, and this new exhibition will no doubt further fan the flames. Their claim that some people just have an agenda to be offended is disingenuous.

It's the press view for Gilbert & George's major exhibition at Tate Modern and the artists are under siege from the world's media. They are amenable to requests from photographers to pose this way and that.

Camera crews send them up and down the giant escalators, waving as they go. Journalists' questions are answered with unfailing politeness. They feel, says George (he's the taller English one with glasses who sounds a bit like Prince Charles except not so strangulated), "quite emotional. We're smiling from both ends. It's every artist's dream to have an exhibition on this scale.

There are pieces here that we haven't seen in over 25 years. They might have been for a show in New York or somewhere else, we'd have hung them, gone to the opening and then they'd have been sold. Now we're being reunited."

Clearly, the show is a big deal, the first retrospective of their work in over 20 years. For the artists, an exhibition on this scale (there are 199 pieces in the show and some of them are enormous) in their home-town was long overdue and fully anticipated. As Gilbert (he's the shorter Italian one with the face that's melancholy in repose) says, "We've spent many years looking over across the river at Tate Modern, waiting for them to pop the question. We've never been part of the establishment, and now, for three months, we are. We had to wait patiently for them to love us a bit more."

The work encompasses the recurring themes of death, hope, life, fear, sex, money, religion and race. "That's it, " says George.

"That's what it's all about. Sexuality and religion are the two most important issues in the world today. We pose the questions, but maybe we don't answer them."

Famously, Gilbert & George live and work in London's East End, and have done for 40 years, since meeting at St Martin's School of Art in 1967. The area and the people who live there provide the raw material and the inspiration for their work . . . "It's our view of the world and how we feel being alive today.

We have no need to travel; it's all there when we walk down the street.

"And because much of it is campaigning art it needs to be visually powerful, to have an immediate impact."

Whatever about campaigning, there are a lot of goodlooking young East End boys in the pictures, and not a woman in sight . . .

something that raises the hackles of some viewers. But, as curators Jan Debbaut and Ben Borthwick explain, the work reflects Gilbert & George's world, and it's male and gay. Women just don't feature.

There are now 20,000 artists and hundreds of galleries in the East End . . . Gilbert & George were the pioneers. Fournier Street in Spitalfields, location of some of the most important houses in London, architecturally speaking, is their base, slap bang in the middle of the radical Muslim heartland. There's a church at one end of the street and a mosque at the other. The newest pieces in the exhibition are a group of six pictures entitled 'Six Bomb Pictures', featuring sandwich board posters from the Evening Standard, comprising a 14 metre triptych entitled 'Bomb' and five other pictures: 'Bomb', 'Bomber', 'Bombers', 'Bombing' and 'Terror' inspired by the London Bombings of 2005.

The artist explains:

"'The Six Bomb Pictures' are the most chilling pictures we have created to date. We believe that as artists we were able to bring something special in thoughts and feelings to this subject, something the media, religious leaders and politicians find difficult to do."

So how do they get on with their neighbours? "A while back eight houses on our street had their doors kicked in, including ours, " says George. "One Hindu lady and the rest were white. We get grief from the fundamentalists because we are non-believers in their midst. They see us as the infidel and they want us out, but we're not going anywhere. Islam is very rigid . . . we can eat their curry but they can't eat our bacon and eggs.

As for the church, the old vicar, a Reverend Eddie Stride, went on television to complain about us. He said we were 'sick, sad and serious', as in seriously criminal. We were quite shocked because he always used to say 'good morning' to us when we met him on the street. But the new vicar is renting the church out to us for a big party tonight, so things are looking up."

Gilbert & George: Major Exhibition Tate Modern runs until 7 May. Admission: �10 (�8 concessions) www. tate. org. uk 00 44 207 887 8888