Perhaps it had to be someone like Michael Nazir-Ali, the first Asian bishop in the Church of England, who would break with convention and finally point out the elephant in the room.

His comments last week about the growing stranglehold of Muslim extremists in some communities revived debate about the future of multiculturalism and provoked a flurry of condemnation. Members of all three political parties immediately clamoured to dismiss him. “I don’t recognise the description that he’s talked about – no-go areas and people feeling intimidated,” said Hazel Blears, the communities secretary.

A quick call to her Labour colleague John Reid, the former home secretary, would almost certainly have helped her to identify at least one of those places. Just over a year ago Reid was heckled by the Muslim extremist Abu Izzadeen in Leytonstone, east London, during a speech on extremism, appropriately. “How dare you come to a Muslim area,” Izzadeen screamed.

That picture is mirrored outside London. One of our country’s biggest and most deprived Muslim areas is Small Heath, in Birmingham, where Dr Tahir Abbas, director of the Centre for the Study of Ethnicity and Culture, was raised. With a dominant Asian monoculture, low social achievement and high unemployment, Small Heath is precisely the kind of insular and disengaged urban ghetto Nazir-Ali was talking about.

Reflecting on his experiences there, Abbas is critical of his peers who don’t stray beyond their area. “They haven’t seen rural Devon, a stately home or Windsor Castle,” he says. That refusal to engage with anything beyond the community is suffocating young Muslims by divorcing them almost entirely from Britain’s cultural heritage and mainstream life.

And their feelings of separation have been further reinforced by the advent of digital broadcasting, which has swelled the number of foreign language television stations in Britain, creating digital ghettos. Islamist movements such as Hizb ut-Tahrir (of which I was once a senior member) have been quick to spot the opportunities this affords them. In 2004 the group launched a campaign aimed at undermining President Pervez Mush-arraf by broadcasting adverts on Asian satellite channels, calling on the Pakistani community in Britain to “stop Busharraf”.

Manzoor Moghal, chairman of the Leicester-based Muslim Forum, is unequivocal about the dangers such Islamification poses. “We have a cultural and social apartheid which fun-damentalists thrive off,” he says.

The point was underscored last summer when Kafeel Ahmed, whom I once knew, was arrested after a Jeep laden with explosives crashed into Glasgow airport. I think Ahmed was first radicalised in Cambridge, where I saw his views become increasingly intolerant, even though the city has a negligible Muslim population. After being exposed to the Islamist culture of separation and confrontation there, he didn’t need to be living in an actual ghetto. He was already sectioning himself off, by giving up his nonMuslim friends and eventually socialising only with those who shared his world-view.

It raises a compelling point that Labour, the Tories and the Liberal Democrats have largely tried to ignore: while the moral ambiguity of multiculturalism means Britain no longer knows what it stands for, our enemies are not just growing ever surer of themselves but are also winning the debate.

For almost three decades now, the witless promotion of cultural relativ-ism under successive governments means that our national identity can simply be reduced to the theme of a courtroom sketch from Monty Python’s Flying Circus – anything goes. Measuring the extent to which this ambiguity has affected perceptions within Britain’s already insular Muslim communities, Abbas told me he surveyed schoolchildren in Small Heath by asking them how many Muslims they thought lived in Britain.

“We had answers around 30m to 50m,” he says, with more than a hint of despondency in his voice (the true figure is 1.6m).

Moghal blames the mosques for this, saying: “They promote a conscious rejection of western values.” He has a point. In many places the prevailing attitude is that sporting a flowing Arab robe symbolises your religiosity while your piety is linked to the length of your beard.

Muslim groups have already reacted with predictable intemperance to the bishop’s comments. “Mr Nazir-Ali is promoting hatred towards Muslims and should resign,” said Mohammed Shafiq of the Ramadhan Foundation, while Ajmal Masroor of the Islamic Society of Britain said the church should “take serious action”.

Their anger vindicates him entirely and in many respects demonstrates that Nazir-Ali’s observations not only are valid, but don’t go far enough. The Glasgow bombings proved that the kinds of no-go area extremists are creating don’t always have to be physical locations.

Muslim attitudes are now so hyper-sensitive that anyone who dares to criticise Islam or Muslims has to think twice – and then some more – before doing so. Publishing a simple cartoon is enough to provoke a serious diplomatic crisis, the ransacking of embassies, mass global protest and at least several deaths.

But it’s not just nonMuslims for whom extremists reserve their hatred. After I wrote about the way British Islamists celebrated Benazir Bhutto’s assassination last month, a number of threats quickly appeared on the internet. “If I meet him I’m going to paste him in his face,” wrote Abu Junayd from Slough on a chat forum. Another commentator said I should “suffer severe punishments in this life and the hereafter”.

Their attitude springs from the Takfiri mind-set, which, in its most extreme forms, underwrites Al-Qaeda’s philosophy by suggesting that anyone who disagrees with Islamism (the extreme, politicised form of Islam) is a legitimate target for attack.

As if to emphasise the point, a statement released on a known Al-Qaeda forum last week specifically called for attacks on moderate Muslims in Britain. Citing the opinions of Muham-mad Ibn Alb al-Wahhab, whose followers are known as Wahhabis, it branded moderates as “aides of the crusaders”.

Seven years after the Cantle report first revealed the extent to which Britain’s different communities are living apart together, it’s still impossible to engage politicians seriously about the future of multiculturalism.

After being heckled by Izzadeen in Leytonstone for “daring” to visit a Muslim area, the home secretary told him: “There is no part of this country that any of us is excluded from.” The knee-jerk reaction to the bishop’s comments suggests we’re still a long way from realising that vision.