Bettina, you seem to understand how some these Muslims feel - its just that you haven't made the connection yet. For some people, blasphemy is worse than murder and once you understand that this is true for them, you should be able to see how strongly they feel. (Rem. understanding != condoning)
To me, you are displaying some of the same hard-line, moral absolutisms that some of these Muslims are showing.
I don't agree with either you or these Muslim (or any other) hard-liners, but I sure understand how you feel. I empathize more with you than I do with them, but that is probably because I am more in touch with my feelings w.r.t. rape and murder of a young girl and (as an atheist) less with the attachment to religious dogma.
I can only guess why the general response by Muslims here in Australia has been much less violent - it may be an infusion of Australian culture/justice system/minority status. Perhaps multiculturalism is working better here. I hope it is not just our (IMO over-reactive) new terrorism/incitement laws.
Tolerance first, free-speech next, religious dogma a poor third.