"I Am Heretic" is a satirical comic, often accompanied with commentary in the form of an article. Download the comic strip from this issue (right click, save as...).
Free speech is an extremely important liberty; it is the foundation of progress, as it allows us to criticize established ideas and systems that are not desirable, like conservative values and inequality. We cannot prohibit criticisms or satire of a religion just because people sincerely believe in it, just like we cannot prohibit criticisms or satire of purely political ideologies or any idea that affects people. In fact, sincerely held beliefs should be scrutinized and criticized more, not less.
As I've argued in my blog post "The danger of free speech" already, the greatest danger to free speech is free speech itself. It is quite ironic, indeed, that some people exercise their right to speak freely to argue against free speech. If we were to limit free speech to protect certain groups, where do we then draw the line? Which groups deserve to be protected and why? Why should an ideology be protected because its subscribers are seen as victims? Who decides this? If we are not allowed to criticize worldviews, how do we know which ones are worthy of protection?
Without free speech, society would never have progressed toward equality. And I'm sure the push for equality was seen as something bad that needed to be fought, in the past, just like criticisms of conservative religions like Islam are viewed today. Yes, there are downsides to free speech. But the pros far outweigh the cons. I am for free speech; I am a liberal; I am Charlie Hebdo. Je suis Charlie!