Also the fact that thousands of European Muslims have gone to Syria and Iraq to fight for ISIS (killing mainly moderate peaceful Muslims in the process). At least two hundred Canadian Muslims traveled to Syria to join ISIS knowing full well what ISIS is all about. All of these people pose a major threat to innocent people in our countries if/when they return home.  European security is tracking thousands of such Muslims. If you read Deutsche Welle online almost every day the police carry out raids on terrorist suspects' apartments. They find guns, ammo, bomb-making materials and ISIS flags. 

So we can't begin to deal with this problem if we can't even call it by its proper name, i.e. Islamist terrorism.