Any other religion is fair game, but not this one. No matter that the magazine satirized Christianity as well.
It isn't about satirizing (though that doesn't help). Islam has a strong tradition of aniconism (something that was also present in Calvinism and Byzantine Iconoclasm), that used to extend to any depiction of a living creature. If you've ever wondered why geometry and calligraphy are so big in medieval Islamic art, it's because in much of the Islamic world (at least early on) depictions of humans and animals weren't acceptable. Strict aniconism is only practiced today by nutty groups like the Taliban, but never has it been acceptable to depict Allah in Islamic art, and only rarely or in Shiite art is the prophet Muhammad commonly depicted (typically with his face obscured).
This actually reminds me of an awesome movie that was made in the '70s about Muhammad and the beginnings of Islam, that never showed him on screen or speaking (the name of it escapes me). I think you see like one shot of his trousers, while he's holding this gnarly sword with two prongs at the end. The people around him speak directly into the camera when talking to him, with no reply, and you hear this recurring music in the background to know he's around.
Point is, there is more to it than being unable to take criticism, since the image itself may be considered a violation, regardless of intent.
Oh huh, I never knew about the aniconism tradition. I knew they were against depictions of Muhammad, to avoid idolatry, in a way similar to Iconoclasm... Didn't know that was (or evolved into?) a general tradition of avoiding depicting people. Neat!
And that movie sounds interesting from a cinematography point of view. Makes sense. Probably this one I think:
https://en.wikipedia.org/wiki/The_Message_%281976_film%29(Google sent me to the more general
https://en.wikipedia.org/wiki/Muhammad_in_film)
Anyway... You're right that it isn't about criticism per se. But it's not really better than that, and it's a rule that extremists are enforcing on people across the globe. They're enforcing it on others, non-Muslims, in contradiction of our own traditions (freedom of speech... and icons all over the place).
It's not something to judge every Muslim by, particularly when they're denouncing the attacks. But huge groups of people *supported* the attacks, and that should be recognized as a problem.
And liberals shouldn't blame the victims in a reflexive perversion of multiculturalism, basically. Charlie Hebdo did nothing wrong.