Fear and greed.
Anything else, including religion, are merely tools in the implementation of evil - not the root cause.
That being said, religion is a tool which seems to be particularly well-suited for making people willing to do evil.
i say 'selfish isolation'
such as many are in belief that they are separate from 'the garden'
that we are not born, bound too or 'created' from mother nature (God)
that is why the old story shares man is 'away from the garden' (God)
all based on selfishness (choice)
find all bad can be idnetified by observing the rules;
measure all choices with:
good: support life to continue (giving of self (energy) for life; live in the contribution)
Bad: loss to the common (taking, stealing, murder, rape, lying, deciet, adultry; all based on selfish gain, pursuits and actions)
'we the people' ....... conscious life, are what can 'think' we are separate from nature/existence/GOD........ and "cause actions against it all", based on choice
instinctive critters don't have these problems.
ever notice a dog can't build nuclear weapons?
'we the people' are the only thing in existence that can be 'evil'
mankind is the cause of all evil ever to exist and it all came by 'choice'