It's nearly 20 years since the fatwa against Salman Rushdie; the judgment by Ayatollah Khomeini, Iran's spiritual leader and head of state, that the author deserved to die for having written the Satanic Verses. Ask the average person on the street about the affair and he or she would probably say it was a straightforward case of Muslims reacting to a blasphemy against their faith, for which the punishment according to that religion is death.

This is not Kenan Malik's view. Talking at the "Battle of Ideas", he offered an alternative explanation – that the headline-grabbing response to the book was the result of an emphasis on identity that had slowly been gaining ground since the 1970s. By the time the Satanic Verses was published identity had become the basis for the allocation of resources and decision-making powers in the community. That hasn't gone away; now, he argues, it helps create the very problems of disintegration and disaffection that it purports to solve; it has helped foster an "internal fatwa" on the part of western liberals.

For Malik, one of the great myths about the Rushdie affair was that it was fuelled by theology. Not so: it had its roots in politics, he says. The book was banned in India as a result of political manoeuvring in advance of the country's elections. Khomeini gave his judgment in a bid to assert leadership of the Muslim world above Saudi Arabia. And conditions were ripe for the conflict to take off in the UK because of the intense factionalism of Muslim groups here.

Alongside that factionalism was an official attitude to minorities that did nothing to contain the fire and everything to encourage its spread. Malik believes multicultural policies created a space for "leaders" of "communities" to emerge who were able to hijack the issue and successfully present their view of it as the authentic one.

Malik might have been disappointed that, when members of the audience were brought in, they weren't so interested in the politics of it as the theology. But he must be used to it by now; there's a desire to know whether or not Islam "really" says that violence in the defence of the faith is justified, about whether the Qur'an is a text apart because Muslims are obliged to view it as inerrant, whereas Christians are not given the same injunction with regard to their Bible.

But I found the audience's reaction at least as instructive as Malik's thesis. Once the talk was over, I overheard a conversation between an older non-Muslim woman and a young Muslim, wearing a veil, who had just stood up to plug her website ("everything you need to know about Islam"). The older woman asked her about the fatwa, wondering how it was that when "your big man" issued a decree, Muslims around the world would obey it. The young woman said she though it had been a very irresponsible thing to do. "But why do they all follow what he says? We don't, if we're offended by something we just ignore it". She went on, "your website says it has 'everything you need to know about Islam', but it isn't everything, is it, because there are all these factions. It's just what you want to tell me." After a few minutes the veiled woman stopped defending herself and just made polite noises. Eventually she escaped.

Whether she was aware of it or not, I think the non-Muslim woman was expressing a frustration at both not being able to pin down and define Muslims at the same time as being angry at "them" for acting in concert, following the orders of a leader in a far-away country. The Muslim woman would have been entitled to feel a bit taken aback at being identified with a 87-year-old Iranian shia who has been dead for 19 years. And yet, I bet she gets that kind of thing all the time.

It's makes about as much sense as taking Rowan Williams to task for the American Christians that picket the funerals of US soldiers, seeing their deaths as God's judgment against America as a latter-day Sodom and Gomorrah. But British Muslims are routinely told what they believe, or asked to justify, speak out against, or condemn heinous crimes which have nothing whatsoever to do with them. It must be quite annoying.

It may well be the case, as Malik says, that multicultural policies have entrenched these kinds of confusions, bred suspicion and resentment. He's certainly right that identity is at the heart of this – not least the idea that there is somewhere an authentic "Muslim identity" to be divined. But the whole thing didn't start on some civil servant's desk. At its root is our willingness to alienate people who are somewhat unfamiliar: to imagine that rather than being just like us, Muslims are definitively different; to imagine that they are all the same, and out to get us; that their creed and their book mysterious book drive them to behave unreasonably. This is, in my opinon, a fantasy, but it's one that has taken hold in the years since the Satanic Verses was published. Maybe changes in policy would help: or have we gone too far down the road of misunderstanding? What, if anything, do you think can be done?