If you can not tell the difference in the two religions one that will kill you if you mock it, demand you convert or die that has not set up one single freedom based society and one that will just look at you in disgust if you mock it then you have missed the boat by a long shot.
The conversation is about fighting for the right of free-speech, not accepting blaspheming art or not. The conversation is about one religion that can not get along with others without killing and enslaving.
The point is, can non-murdering Muslims ever join non-murdering Christians (and almost all are) in a march, and temporarily suspend their offense at depictions they don't like in the name of free speech rights?
Nevertheless, it's wrong for the slogan to be "I am Charlie Hebdo."
If somebody --- deranged or not, religious or not --- ever wipes out the Hustler magazine staff (which I of course firmly and unambiguously condemn), will we protest and show our bona-fides by carrying signs that say, "I AM LARRY FLYNT"?