Why is this so?

I am a rationalist and by training and temperament, I am allergic to any set of religious dictates being imposed on my mind. Being so, I have always felt that people who follow some faiths are completely enslaved by their religious elders who are for the most part totally ignorant of logic and reason. I wonder why in the name of religion, to take recent examples, the people who profess to embrace Islam commit dastardly acts of cruelty and violence in the hope that that they will attain to martyrdom and receive pleasures in heaven, that are denied to them in actual living. Do they not realise after some reflection that there is nothing to life after we are dead, whatever the religious people might say? Do they ever stop to think that they are misguided and that they heap nothing but misery and distress on all concerned? When are theses people going to think about these matters? Please comment with reason. Thank you.