We don't properly discriminate. We never discriminate properly when we're dealing with another group and one of the big problems about religion is that religious people don't know that they are probably as flagrant in these misjudgments as irreligious people.
Every character lives in ever actor and if you're doing your job right, you're just accessing that part of your fantasy life. I can kill someone just as quickly as I can have sex with someone. You can switch that instinct, no matter what - you can pretend anything.