"I am Charlie."
Well, I hope I'm actually little like the person Charlie or his publication. My impression is that Charlie Hebdo was an in-your-face publication that was hostile and insulting toward religions of all sort.
We are Charlie today because we stand against the kind of person that marches into a place and murders a bunch of people. We would be against someone calling himself a Christian who marched into an abortion clinic and killed a bunch of people. We are against terrorists. If God really needed people like this, he wouldn't be much of a god.
Freedom of religion is not absolute in that sense, not in a modern, representational democracy. Your religion doesn't give you the freedom to kill people. Indeed, since your children are individuals protected by the fundamentals of democracy, there is a point where you are not free to have your religious way with your children. For example, if for religious reasons you refuse to let your child have a blood transfusion, a democratic society will give them one anyway.
Given the circumstances, the French right now are tempted to think freedom of speech an absolute. But none of these privileges of a modern democracy are absolutes. There is a point at which a radical cleric crosses an ambiguous line between stating ideas and making violence happen. Whatever that point is, it is the point where freedom of speech ends.
As a side note, words can actually be more hurtful than physical actions, as most people with multiple children can attest. The cutting words of a sharp-tongued child are often more hurtful than the physical response of a less verbal sibling. You cannot neatly partition off speech from action, as speech-act theory attests. Speech is action, and there is a point where its action crosses a line.
"Charlie" didn't cross that line. So this discussion is merely the reflection of someone who doesn't live in France today.
Today, "je suis Charlie."