GK Chesterton once said that to criticise religion because it leads people to kill each other is like criticising love because it has the same effect. All the best things we have, when abused, will cause bad things to happen. The need for sacrifice, to obey, to make a gift of your life is in all of us and it's a deep thing. In the Islamic world today, people are trying to rejoin themselves to an antiquated and ancient faith and the result is massive violence when they encounter people who have not done that. We'd say that sense of sacrifice is good but only if you're sacrificing your own life; once you sacrifice another's life you've overstepped the mark.