So why mention it at all?
What is clear was this person's intolerance of any other view than his own, and it seems to be that much of human conflict is based on that intolerance, whether religion is used as the excuse or not. Within religious groups there are fundamentalist/fanatics who cannot or will not tolerate another viewpoint, just as atheists will not tolerate the religious views of others, or make little effort to understand them.
Outside religion, there is intolerance that makes for conflict - cyclists and motorists for example - some fanataical cyclists seem to think that traffic laws don't (or shouldn't) apply to them and act selfishly. Equally, some motorists take the view that cyclists should be banned from the roads because they slow their journey time for a few seconds.
We see intolerance elsewhere - on HEXUS, there are the Apple/anti-apple factions; Andriod/Ios factions. Actually pointless arguments (in those cases) because ultimately it comes down to personal prefereance - as does religion, or otherwise.
The fact that someone with some form of mental problem (and I don't think that anyone would disagree that someone planting a bomb for indiscriminate killing, or murdering children at a youth camp has to be a few sandwiches short of a picnic) chooses to justify his action on some quasi-religious or cultural intolerance grounds is largely irrelevant. If that was the way he was wired, he'd find always some justification for his actions.
Ultimately he is no better than a spoilt child who didn't get what he wanted - being an adult, his temper tantrum had further reaching consequences, and manifested itself in the way we saw over the weekend.
So a little more tolerance all round wouldn't come amiss.