Why is it so difficult to accept that Islam has deep rooted problems? We have 14 centuries of evidence and a core text which gives explicit sanction to every single action of Islamic State and all the actions of the various Islamic extremist groups. Yet still we stick with this ridiculous notion that it's all some sort of a misunderstanding. That an essentially peaceful religion is being twisted by a small number of fanatics.
There's a line in the film Full Metal Jacket which so brilliantly sums up the main attitude behind this brilliantly. When confronted with a young private who appears to have doubts about the war he explains that they are helping the Vietnamese because "inside every gook there's an American trying to get out." In a politically incorrect way, this articulates the very politically correct conceit at the core of the multicultural dogma - that our western values are universal human values, and only entrenched tyranny and ancient prejudice is preventing the world from living up to them.
The reality is a little more complex. Even if this is true on a genetic level, deep cultural values are ingrained in people from the moment they enter the world, and clearly not everyone aspires to the secular, western lifestyle. The tyrannies are as much a result of the culture as the culture a result of the tyranny, and thus the prejudices become self-reinforcing.
In this way 'diversity' tends not to lead to a united whole where everyone converges on a central idea and maintains superficial differences, but quite the reverse. People converge on superficial ideas while the deep rooted differences actually grow as they regard each others cultures with horror and recoil into self-propagating isolation.
In this way Muslim communities across the western world are more isolated than they were 30 years ago. Young Muslims born in western countries are more radical than their parents. Young women are more likely to wear hijabs and young men more likely to join IS. The entire narrative and ideology behind peaceful coexistence with curry and real ale has fallen apart.
A collapsing narrative of this type is difficult to process. The film Goodbye Lenin! captures this beautifully, following an East German family attempting to hide the collapse of Soviet Communism from their bedridden mother. It is something that people have a deep emotional attachment to and when defending it logically fails they will swear black is white rather than change their premises.
Thus David Cameron can say with utter certainty that Islam is a religion of peace just days after the Paris atrocity, sanctioned by a man with a Doctorate in Islamic studies and perpetrated by devout Muslims shouting 'Allahu Akbar.' Thus the media greeted with delight the advert in the Telegraph taken out by the Muslim Council of Britain condemning the attacks in the loosest terms. Thus the entire body of incredibly detailed research by the likes of Robert Spencer and Daniel Pipes, along with the pronouncements of Muslim scholars themselves can be completely ignored in favour of vague platitudes.
The narrative must survive, even if it is wrong, because if it fails then all manner of assumptions which rest upon it also fail.