Shooting people is wrong.
I want to get this out of the way. When twelve people are killed by violence, whoever they are, for whatever reason, that is a tragedy and a waste. To murder someone by violence is the greatest crime imaginable—with the sole and narrow exception of using violence against people who directly and immediately threaten violence themselves.
There is no such thing as speech so hateful or offensive it somehow “justifies” or “legitimizes” the use of violence. The right to free expression—that’s a universal. The fear of violence should not determine what one does or does not say. In an ideal world that simply would not be a consideration because a violent reaction to speech would not be allowed to occur—in the imperfect world we live in, we should strive for the standard of knowing what we say might attract violence but speaking out as though the threat did not exist. That is the essence of the virtue we call “courage,” and the staff of Charlie Hebdo displayed it and should be honored for possessing it.