The cartoon only became a sensation, and was reprinted millions of times around the world, AFTER the attack. Even still, if I'm offended by p rnography, I don't go around killing people who work at those magazines or who make those movies.
And you might think that what the Charlie Hebdo people did was 'wrong' in your own worldview, but they broke no law, committed no crime, and did nothing 'wrong' in the eyes of the vast majority of French people. You may think it was wrong, but I may think it's wrong for women to cover their faces. That's only an opinion based on your point of view.
But walking into an office with guns and shooting people is wrong. To compare the two actions and create some sort of sense of equivalency is something we aren't ever going to agree about.