davebro - // Dunno if it's a significant factor but it seems these sorts of murderers are pretty much a failure in every other aspect of their lives so they really have nothing left to lose except maybe the continuation of a miserable existence. //
If you accept as a starting point, that murdering a stranger is the act of a psychopath, and that dressing it up with justifications such as religion does not alter that fundamental basic fact, then you also accept as a starting point that all normal points of reference are out of the window.
That means that this particular instance of psychopathy finds a home in bonding together with others in a 'gang' mentality that gives structure and meaning to an otherwise directionless life.
That sense of involvement and support can often elicit a need to put something into the organisation, not only to underline the newfound spirit of belonging, but to pay back the organisation with some definitive and observable act or pattern of behaviour.
This often starts with simply developing hostility to anyone who is not a part of the organisation, the 'brotherhood', and increases a distorted sense of superiority which is the pendulum swing of previously harboured feelings of insecurity an inadequacy.
That can then escalate to a pitch whereby the psychopath develops such a level of imagined superiority, and the need to express that feeling in as dramatic and high-profile a way as possible, and hey presto, you have a religious fanatic ready and willing to kill strangers.
But the vital point to remember is that these actions are motivated by escalating psychopathic impulses, which are not directly connected to the Muslim faith - they simply provide a convenient framework whereby the psychopath is free to exaggerate and distort religious teaching until it can be twisted to fit the murderous behaviour that follows, even though for the vast majority of followers of that faith, that is not ever seen as a way to express their beliefs.