I agree that it comes from within. I believe that  Integrating our own shadow is the way to dissolving the evil we perceive to be outside of ourselves.

It certainly exists!! And that evil comes from your being, some people channel it in a positive or negative way... but it is in you..!! Everything you do will at some point come back to you... there is no escape!! I read a book or rather an essay in PDF... on how to make that evil turn to your advantage... it was a long time ago..