I am not offended by their murder, I am outraged by it. I used to read Charlie Hebdo when I was living in France. The death of these journalists, artists, policemen sadens me. The people responsible need to be found and jailed for life as is the penalty for first degree murder under french law, after proper judicial process.
But let's be realistic. Terrorism of pretty much anykind is only a minor nuisance in the western world (not sure about the rest of the world). But we talk a lot about it because it appears random and it appeals to our deepest fear: the collapse of society.
But we need to make the difference between the terrorist and the group they claim to make their act for. When the IRA was very active in the 90s, I did not blame the Irish people. When the FLNC was active, I did not blame the people of Corsica. When the "army of god" bombed the abortion clinics in the 90's, I did not blame the Christians.
Fanatics are a problem. They must be stopped. Islam, like all religions, is defined by the belief of those that follow it.