Is their reaction to the Turkey earthquake, There were roughly 51k killed, and their cartoon was that this was good because that was less muslims they had to kill.
Their 'Mohammed edition' was a full comic about how much they hated muslims. It was pure racism and in many countries they would have been prosecuted for hate speech.
They are a hate group.
This is the meaning of two wrongs don't make a right. Charlie Hebdo are disgusting, the people who attacked them so severely were absolutely wrong, but neither act makes either of them right.