Salman Rushdie is ready for his next role. "I'll be Marlon Brando in a turban," he says. His friend Deepa Mehta, who has just directed the author's adaptation of the Booker-winning novel Midnight's Children, wants Rushdie to play an ageing godfather in her new movie, set among western Canada's feuding Sikh gangs.

"I really want to do it," he says. "It'll be Tarantino with brown people." It is not the first time Rushdie has been offered a menacing film role. Paul Auster asked him to play a sinister interrogator who gives Harvey Keitel the third degree in Lulu on the Bridge. Alain Robbe-Grillet urged Rushdie to play a suspicious doctor who tended to Jean-Louis Trintignant's crashed pilot in the Cambodian jungle. "Maybe they saw something evil in me," he laughs as we talk at the Bloomsbury offices of his literary agent.

Rushdie turned those film roles down, but did play an approximation of himself in the 2001 movie Bridget Jones's Diary at the suggestion of novelist Helen Fielding. He was never asked to play himself in the 1990 Pakistani film International Gorillay, about jihadists who vow to kill an author called "Salman Rushdie". At the end of the film, "Rushdie" is terminated, not by jihadists, but by three large Qur'ans hanging from the sky that reduce him to dust in punishment for slurring Islam in his novel The Satanic Verses. The real Salman Rushdie played a key role in ensuring that film's UK release: Britain's film censors were set to refuse it a certificate because it was inflammatory, but Rushdie assured them he wouldn't sue for libel and so it was released. "It was a piece of crap but banning it would only have glamorised it," he says.

I take a sidelong glance at Rushdie, looking for the devil in the 65-year-old writer. His goatee recalls venal drug kingpin Fernando Rey's in The French Connection. His eyelids still droop slightly despite an operation for ptosis a few years ago and his eyebrows point diagonally to the bridge of his nose. He could use these natural assets to make himself look diabolical, but not today.

We are meeting to discuss Rushdie's longest-running role, his 13-year performance as a character called Joseph Anton. This was the pseudonym he took after going into hiding following the fatwa declared upon him by Iran's Ayatollah Khomeini on Valentine's Day 1989. His protection officers suggested he choose another name to increase his security when he turned up at a new home (though being flanked by four armed men in bulletproof Jaguars usually did the trick). "Probably better not to make it an Indian name," counselled his minder Stan. And so, Rushdie writes, he became "an invisible man in a whiteface mask". Joseph was Conrad's first name, Anton was Chekhov's. He was Mr Anton until March 27 2002, when the police Jaguars finally drove out of his life for the last time.

That pseudonym now supplies the title for his new 636-page memoir. Why would he want to revisit those years? During that time his first wife Clarissa died of cancer, his second and third marriages broke up, his fourth was shaky, his Japanese editor was murdered, his Norwegian publisher shot, his Italian translator stabbed, hundreds died in riots protesting against his novel, his books were burned from Bradford to Islamabad, he did things that still make him burn with shame and he found that writers he admired such as John Berger and John Le Carré, both writing in the Guardian, attacked him for not withdrawing the novel.

"For a long time I didn't want to write this because I felt it would be too upsetting. But writing it actually wasn't." But why write it at all? Surely memoir is the basest of literary genres, where scores are unedifyingly settled. Rushdie demurs: "Well, I didn't want to write 600 pages of getting even. I thought I would try to be as understanding as possible to everybody else and as rough as possible on myself. I decided not to varnish stuff."

Rushdie isn't, to my mind, only rough on himself. His second wife, the novelist Marianne Wiggins, surely will not enjoy reading the passages in which Rushdie presents her as delusional. She becomes, if the memoir is to be believed, an undermining presence during Rushdie's adversity, giving an interview in which she calls him weak and vain. The couple divorced in 1993. It is hard not to read these passages in Joseph Anton as belated payback.

Did he show Marianne the manuscript? "No, she can buy a copy," he says.

By contrast, his third and fourth wives, Elizabeth West and Padma Lakshmi, were consulted about the book, as was his son Zafar whose mother Clarissa (Rushdie's first wife) died during the fatwa years. "Elizabeth was one of the first readers of the book and, after correcting some passages, she signed off on it." She signed off, presumably, on the delicious scene in a New York room in which she meets Padma Lakshmi, who would become Rushdie's next wife, and eviscerates the Indian supermodel, TV chef and actor in ripe language that her husband was surprised she could use so eloquently.

Lakshmi, from whom he was divorced in 2007 after three years of marriage said, according to Rushdie: "Just tell me what's in the book so I don't get blindsided." The fourth Mrs Rushdie will not like the passage in which he watches her "pose and pirouette" for the paparazzi outside a Vanity Fair dinner in Hollywood. "She's having sex," Rushdie writes, "sex with hundreds of men at the same time and they don't even get to touch her, there's no way an actual man can compete with that."

A protest against The Satanic Verses in New York in 1989. Photograph: Ezio Petersen/Bettmann/CORBIS

If he is rough on himself, it is for becoming briefly, as he puts it, "a dentist's zombie". On Christmas Eve 1990, at the behest of six Muslim scholars whom he had agreed to meet at Paddington Green police station, he signed a paper saying he had intended no offence to Islam and re-embraced the religion. The man who brokered this meeting, Harley Street dentist Hesham el-Essawy sought to return Rushdie to the faith into which he had been born in Bombay in 1947.

Soon after that meeting he wrote an article called "Why I am a Muslim" for The Times. "I am certainly not a good Muslim," he wrote then. "But I am able now to say that I am Muslim; in fact it is a source of happiness to say that I am now inside, and a part of, the community whose values have always been closest to my heart."

"I was physically sick after that," he recalls. "I felt I had lost my mind. Reading through my journals of that time, I see it was the blackest period. I became the dentist's zombie, thinking he was giving me [spiritual] Novocain. But everybody who loved me told me I was insane." He remembers his sister, Sameen, ringing him from across London after she heard of her brother's abject and futile attempt to appease. "She said: 'I don't fucking believe it. Have you lost your mind?' The problem was I had acted alone, without consulting my supportive friends and family."

He doesn't entirely regret his temporary zombification. "It was hitting the bottom and one of the benefits of hitting bottom is you know where the bottom is." He would never succumb to such approaches again. Instead he repudiated his supposed faith, setting himself selfconsciously in the tradition of writers such as Osip Mandelstam and Federico García Lorca who stood up to tyrants. He describes himself today as "a profoundly irreligious man" and "of the Hitchens camp" (his late friend Christopher Hitchens, wrote the bestseller God is Not Great). In Joseph Anton, Rushdie argues that there is a need for blasphemy: "The writers of the French enlightenment had deliberately used blasphemy as a weapon, refusing to accept the power of the Church to set limiting points on thought." He stands in that tradition, though it is Muslim mullahs rather than Christian clerics whose power he contests.

At the start of Joseph Anton, Rushdie recalls what he said on US TV the day he received the Ayatollah's unfunny Valentine. "I wish I'd written a more critical book," he told CBS, adding that he did not feel his book was especially critical of Islam, but that a religion whose leaders behaved in this way could probably do with a little criticism.

"I'm proud of myself for saying that in deep shock," he says. So if you redrafted The Satanic Verses today, knowing the miseries the fatwa caused you, you'd have written something even more critical of Islam? "Definitely. Oh yes. But The Satanic Verses isn't – or is not only – about Islam. It deals with the origin story of religion, closely following Islam. It's about the nature of revelation, about the seeing of visions. There are close parallels between Joan of Arc and St John the Divine's revelations and Muhammad's descriptions of seeing the Angel Gabriel. It seems to me that's a subjective reality, not an objective one. If you'd been standing with Muhammad would you have seen this big angel? Probably not, but at the same time Muhammad was not making up what he saw. For him it's not a fiction. That's interesting to write about."

He also found it interesting to write about the moment Muhammad was seduced by the devil. The satanic verses of Rushdie's novel were those Muhammad believed were dictated to him by the angel Gabriel. They said that the pagan goddesses worshipped in Mecca "are exalted females whose intercession is to be desired" – a contradiction of nascent monotheistic Islamic orthodoxy. Only later did Muhammad repudiate these verses, argues Rushdie, saying he was deceived by the devil, disguised as the archangel. into believing them.

As a history undergraduate at Cambridge, 20 years before he wrote The Satanic Verses, Rushdie had written about this historical Muhammad and wondered why 1,400 years ago the prophet temporarily accepted the first false revelation as true. One possible answer, Rushdie argued, following certain western scholars of Islam, was that Muhammad was a political figure who, briefly, realised that his shaky Mecca power base could be made more secure if the monotheistic religion he founded could make accommodations with followers of then-popular pagan deities. But this makes the founder of Islam look more like canny politician than divine vessel, a seeming slur on Islam at the moment of its birth. Worse yet, in Rushdie's novel the tempted prophet is called Mahound, a derogatory name used by crusaders.

For many Muslims Rushdie was attacking their religion and mocking its prophet. "I don't mock Muhammad," says Rushdie. "I treat him as someone who behaved pretty well. When he came back to Mecca in triumph he didn't kill many people."

At the end of Joseph Anton, Rushdie writes that he is not sure if the battle over The Satanic Verses ended in victory or defeat. Why not? "Well, the book is still in print and the author wasn't suppressed so it was a victory in that sense. But the fear and menaces have grown."

That is an understatement. We are meeting on Friday after the murder of the US ambassador to Libya and as many Muslims spend their holy day attacking western embassies across north Africa and beyond, in protest at a film, the Innocence of Muslims, that slurs Islam. "The film is clearly a malevolent piece of garbage," says Rushdie. "The civilised response would be to say of the director: 'Fuck him. Let's get on with our day.' What's not civilised is to hold America responsible for everything that happens in its borders. That's crap. Even if that were true, to respond with physical attacks and believe it's OK to attack people because you're upset at this thing, that's an improper reaction. The Muslim world needs to get out of that mindset."

He doubts it will. The downside of the Arab spring for him is the rise of Salafism. "That extremist form of Islam has risen since the Arab Spring in those countries where there were revolutions." Worse yet, western liberals have bent the knee to the sensibilities of the most extreme Muslims, he argues. If Rushdie presented the manuscript of a new novel more critical of Islam than The Satanic Verses to his agent today would he be able to sell it? "Probably not."

He cites as a case in point Channel 4's decision last week to cancel a screening at its London HQ of Islam: The Untold History, following complaints and online threats to its presenter, the historian Tom Holland. It is a programme that examines the origins of the religion from much the same historicising perspective as that which interested Rushdie.

"The refrain is: 'Oh dear, Muslims might be angry and we must respect them.' Not true. When people do the cowardly thing, it's not about respect, it's about fear." That's debatable, but what is certainly true is that Channel 4 has not wholly bent the knee: Holland's series can still be viewed online on Channel 4OD.

The west, Rushdie argues in Joseph Anton, is partly responsible for the rise of Islamic fundamentalism. Why? "The west was involved in toppling the Mossadegh government. That ultimately led to the Iranian revolution. That's one part." Another part is the west's support for the House of Saud. He writes: "To place the House of Saud on the Throne that Sits Over the Oil might well look like the greatest foreign policy error of the Western powers, because the Sauds had used their unlimited oil wealth to build schools (madrassas) to propagate the extremist, puritanical ideology of their beloved (and previously marginal) Muhammad ibn Abd al-Wahhab, and as a result Wahhabism had grown from its tiny cult origins to overrun the Arab world. Its rise gave confidence and energy to other Islamic extremists.'"

But not entirely the west's fault? "A certain part of what's happened in the Muslim world you would have to describe as a self-inflicted wound. When I was a boy I was told of the great cities of Beirut, Baghdad and Tehran. They were sophisticated, beautiful places where different cultures mixed. In my lifetime, they've gone from that to being disaster zones."

Recently, he visited the reopened Islamic wing of the Metropolitan Museum of Art in New York. "There was stuff of heartstopping beauty – treasures, jewellery, plates. So many wonderful things. The problem is it [Islam] has developed into a narrow ideology. Islam won't produce such jewels this century."

Rushdie has lived for the past decade in New York, though he maintains a home in London. Did you lure Martin Amis from London to Brooklyn? "No. Both of us live there because we love it. Ian [McEwan] says he's feeling lonely." One thing that thrills him about living in the States is how immigrant writers are revivifying its literary culture, in a way that – perhaps – he and others did in Britain a few decades ago. "American literature has always been immigrant." Now, he says, writers such as the Chinese-born Yiyun Li and Dominican-born Junot Díaz are making American literature unprecedentedly rich. "Its literature has never reached so far, into as many different worlds." So who does he admire among this rain-soaked dime of a country's writers? "David Mitchell. I think he's just such an extraordinary talent with the ability to write so many different novels. Zadie's new book [he means Zadie Smith's NW] looks like a return to White Teeth territory so I'm looking forward to reading it."

Are you writing? He points to the hulking tome Joseph Anton: "I've just written 600 pages. Give me a break." He prefers to talk about the film of Midnight's Children which opens at the London Film Festival next month. It has received lukewarm reviews, I say. "Including, a nasty piece in the Guardian," says Rushdie. Catherine Shoard's two-star review was, I submit, not nasty, though it did portray Rushdie, who adapted, executive produced and did the film's narrative voiceover, as quite controlling. Is he? "All I can say is that the Toronto audience gave it a standing ovation." It has been a long time coming: he once wrote a script for a BBC TV dramatisation that was never made and the movie shoot was delayed for several days after the Iranian foreign minister appealed to Sri Lanka not to permit filming.

The last time I interviewed Rushdie was in Miami in 2008. He was 25 days into a 29-city US book tour to promote The Enchantress of Florence. In the parking lot outside there were three police cruisers. Just in case. Today, as he steps out into London's evening sunshine to get a cab to his launch party, there are no cops, armed or otherwise, to be seen. It has been like that in Britain for 10 years, ever since his minders revoked his membership of the Level One Club. Before, that club had three members all of whom required 24/7 protection: the queen, the prime minister and a certain Mr Anton. "Then in 2002, I dropped to level three or four, and basically then you look after yourself." Tonight, he is a free man. He aims to play that part for the rest of his life.

• Joseph Anton is published by Jonathan Cape tomorrow at £25. To order a copy for £20 with free p&p go to guardian.co.uk/bookshop or call 0330 3336846

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