Your thread doesn't say "how peaceful is Islam in 2015" or the 21st century, or what have you, so if nothing else that clarification was needed.
Secondly, the acts of IS and other islamists are gruesome, no doubt, and born out of great hatred. However, our (the western world's) casual bombing of targets in the 3rd world and elsewhere is every bit as destructive, and the indifference with which we can outsource these things and not give a damn that blood is being spilt with our taxes backing them.
We've never been on the other side. I have a friend from Palestine, he's just gotten into the municipal council of my neighbouring municipality, and is a sharp and politically engaged fella. Once he got in there were a few pieces on him and his past... One of them outlined how he went to a friend's place for a barbecue, only to hear bombs go off in the distance. When he made it to the friend's place he found that it had been fecked up proper, and his friend was spread all over the place. Him and his mates go with plastic bags and pick up pieces of their friend. Hands, fingers and other stuff lying around, eyeballs in bushes... I can't imagine that. I can't imagine the other story mentioned in that piece, where he saw his uncle's charred body, clutching his infant daughter. Good Christians support Israeli atrocities, that don't seem to hit home like Paris did, does it?
These are just some of his stories, and he's one man, from one country. I, for one, can't fathom a life like that, having experienced that, and the hatred that could stir. It makes me object strongly to saying that it's something inherently to do with Islam, rather than a manifestation of it under dire conditions.
And this is coming from an atheist, who's ready to slate religion at the drop of a hat.