For one thing, before the 20th century, there were plenty of genocides. We tend to forget about them, partly because they weren't as well documented and partly because, until recently, people didn't care. We used euphemisms like 'sackings' and 'sieges' instead of calling them 'genocides.'
...the scientific attitude implies what I call the postulate of objectivity—that is to say, the fundamental postulate that there is no plan, that there is no intention in the universe. Now, this is basically incompatible with virtually all the religious or metaphysical systems whatever, all of which try to show that there is some sort of harmony between man and the universe and that man is a product—predictable if not indispensable—of the evolution of the universe.
In the 1970s, many intellectuals had become political radicals. Marxism was correct, liberalism was for wimps, and Marx had pronounced that 'the ruling ideas of each age have ever been the ideas of its ruling class.'
Why do people believe that there are dangerous implications of the idea that the mind is a product of the brain, that the brain is organized in part by the genome, and that the genome was shaped by natural selection?
People who want to study religion usually have an ax to grind. They either want to defend their favorite religion from its critics or want to demonstrate the irrationality and futility of religion, and this tends to infect their methods with bias.
Dixit 
