They are not "radical Muslims". They are drunken/drugged up angry losers. Some of these have been found to run night clubs and buying "The Koran For Dummies".
This, actually, I find myself agreeing with. Considering many of the last few attacks, I'd bet this to be a better description of the perpetrators than the one IS is so quick to attribute to them ("our soldiers", etc).
Worryingly, it makes them very hard to find in time for any intelligence organisation.