Freedom of speech at a great cost

I am all for freedom of speech. But all what price? There are magazines who thrive on insulting the religious beliefs of others, Charlie Hebdo among them. These insults have cost the lives of many and heartache to their loved ones. I wonder do the journalists of these magazines ever think that those insults may cause the death of an innocent person? Extremists need no excuse to take a life but why did the French give them an excuse?