The UK government could (and to some extent should) consider the relationship between 'ordinary muslims' and the Islamic extremists in same way that the Guatemalan state used to consider the one between Marxist guerrillas and the indigenous population.
That's not to say that it would be advised to reach the same drastic conclusions - as the institutionalised hate-crimes (relocation, genocide) perpetrated against the Indians over during the eighties only strengthened the originally quite tenuous links between ideological communism and native collectivism.
If there's one thing revolutionary types have learned over the past one hundred or so years it's that your basic peasant is some way from being a model card-carrying party member. So, you would be right to expect the same sort of dissonance between your 'ordinary muslim' and the generic AK-waving terrorist.
Yet important points of contact do exist. Following the same comparison, the modernising nation state in Guatemala was confronted with a group of people whose basic consciousness was at serious variance with the politically dominant system of values. (Perceived ethnicity was of course another important level of contention.) This sort of situation provides a substrate for violent insurgency which committed extremists (and many of the actions taken against them) could over time puff up significantly.
Now it seems to me that there's is a fair deal of naivety (and creeping hypocrisy) in contemporary liberalism. The working assumption that open social systems can assimilate closed ones without unpredictable side-effects is surely worth examining. It's clearly no longer just a question of which team the locals cheer for at the test match at Heddingly.
Let's start with some useful generalisations: In any organic system at the celular, individual and social level there is always a definable tension between open-pluralistic and closed-collective patterns of organisation and behaviour. In human societies this tension is the principal yin-yang of underlying political process.
We are fortunate that classical Greece provides us with two essential examples of the basic alternatives: Athens (open and pluralistic) and Sparta (closed, collective, totalitarian even). We are able to see how the Athenian system responded to military defeat by Sparta in practice by closing up politically, whilst over in theory Plato's Republic provided a comprehensive argument for a well-structured authoritarian state run by an elite oligarchy.
These basic tendencies exist within most religions as well. Chritianity has over the centuries featured strong ascetic, sensualist, authoritarian, democratic, personal and collectivist currents. Ever since Jesus made his little "give unto Caesar" speech and then Caesar in the form of Constantine took what was apparently his to take, there has been a fundamental political ambiguity in the Christian faith. (All of which means that it has been able to adapt to many different historical circumstances, but which also makes any discussion about the essence and impact of Christianity rather circular.)
The open society in the west has generally congratulated itself for the way that it burned away most of the malignant despotism inherent in its most of own denominations. It should not however assume that the same treatment will be efficacious in all cases.
In the other desert monotheisms the authoritarian model is more dominant. Yesterday Dr Hani Al-Siba'i reminded Al Jazeera that Islamic law doesn't recognise the term civilian. Indeed, Islam was specifically planned with theocracy in mind and Mohammed's revelation involved a violent purification of what he and his followers saw as the corrupt, pluralistic society that then existed in Mecca. The resulting religious block has only on a handful of occasions been diverted very far from the essence of this sternly disapproving worldview. (One should not forget either that while we Europeans were being Enlightened, America was busy becoming America, and that fascism of the Christian variety is alive and well in the red states. )
The western world appeared to deal definitively with its totalitarian demons in the middle of the last century. Yet rarely in biology does a pure individual or collective unit exist - the system as a whole retains the right to rebalance itself along one or other principle according to prevailing circumstances. Modern government gives one or other the opportunity to monopolise the use of violence - so when the fascist tendency can no longer hog the state aparatus, it eventually resurfaces as banditry. And in the particular instance that we now face, a virulently form of religious-fundamentalist banditry. (That the closed society these Islamo-bandidos fantasise about doesn't necessarily have to be realised on this Earth, makes it that much more pernicious in nature and nihilistic in its expression.)
In this religious guise it is harder for liberals to take on directly. Being based on 'faith', it blends in with a wider community of the faithful whose personal convictions (even when they involve things that liberal society otherwise finds distasteful) must be tolerated. So the liberal state resorts to cheating - it retains the surface rhetoric of liberalism while underneath its methods of self-defence harden along authoritarian lines.
On a wider level the open liberal society has been surreptitiously restructuring in order to preserve the cultural and economic benefits of freedom, whilst at the same time effectively closing down on other levels. The principal neurosis of 'free' citizens now revolves around choice, the expansion of which offers an antidote to the obvious narrowing of other aspects of our society - we keep consuming in order to preserve the sense of things feeling that they are geeting ever better.
Frankly this is all very ostrich-like. We are guilty of systematically confusing the opportunities to express our individuality that consumerism provides with the altogether bulkier concept of freedom. This should be a cause for concern amongst 'ordinary westerners' too. There are aspects of our society that may well deserve the disdain of more traditional value systems and it would be delusional to suppose that the problem would go away if only these people could get with the programme and just buy stuff.