Another way of looking at it...
Uneducated folks live in a fuckin' desert and struggle for every scrap of comfort. They have absolutely no idea about the 'real world' (as we would call it), just what the vile bullshit that us lot call 'religion', pumped into their heads, over and over again... and also that evil thing called 'The Western World', all rich and gloating and white and throwing down incinerating bombs that murder families, all in the name of a city called 'Paris', that you've never heard of... but you've seen the corpses and heard the screams and smelled the cooking blood...

So, some powerful people, your Holy Men that you worship, come down and call the western world 'The Devil'. Who wouldn't want to kill The Devil, especially if (a) you're utterly ignorant of world issues, (b) you've seen so much destruction and (c) THE DEVIL IS COMING TO KILL YOU!!!
Plus, you will go to Heaven if you destroy yourself, end your miserable life and relax in Paradise forever...
I'm not, for a single second, excusing what has been done, but let's please look at what's ben put to those poor ignorant people... RELIGION is just an awful thing...