Let’s start by getting something straight: the attack on the satirical French magazine Charlie Hebdo was terrorism. It was planned, carefully targeted, and intended to spur people other than those who were attacked to take actions in line with the terrorists’ goals. Unable to accomplish these goals via conventional means, the perpetrators chose the tactic of terrorism instead. The strategic goals of the terrorists are what are important in understanding their actions and how to counter them, not the ideas they toss around as easy supposed justifications for their actions.
The actual identity of the target was symbolically important but incidental to the strategic goal of the attack. Yes, the perpetrators might have found Charlie Hebdo’s cartoons deeply offensive. But they also surely knew that the magazine is not unique in its offensiveness, has relatively small print numbers, and would only gain more attention after the attack. In fact, the magazine now plans a print run over thirty times greater than usual. So in what way does that target suit their goals?