it seems to me like what this is bringing up for us (as a group in this thread, not "us" as in the human race in general) is whether we believe in evil at all- the current line of thinking defines evil as sociopathy- it is an illness (an untreatable illness, yes, but something that grows from events and conditions that predate the individual's moral responsibility)
do we think people who commit horrors are evil or that they are ill?
how could you do commit an atrocity if you cared at all about life? and how can you not care unless you are just missing something inside? and isn't that illness?