naomi - // Not that Islam is wholly an abstract concept - but yes it is possible - and it's absolutely right to do so. //
An abstract concept is an absolute, something either is an abstract concept, or it is not, there are no degrees.
Secondly, for responsibility to be accepted, it has to be apportioned to one or more individuals personally, and I would hope you are not suggesting that every Muslim should accept responsibility for the actions of a tiny minority of psychopaths claiming to act with their faith as a peg on which they peg their murderous impulses.