'Evil' is a word, which we human beings have invented to describe certain modes of behaviour, which the majority of the population find to be unacceptable. Our view of what constitutes 'evil' changes depending on our political, cultural and religious backgrounds. For example, an ardent Nazi may not think it evil to hate Jews, unlike most non-Nazis. Now if Germany had won WWII then it seems likely that the dominant paradigm would be one, in which anti-Jewish feeling was something to be encouraged and feeling sympathetic towards Jews looked upon as 'evil'.
If we try and think outside our discourse for a moment, we might imagine that a being, such a Iluvatar, would not necessarily operate on the same level as we do. Those
events Iluvatar sets in motion may be interpretated by lesser beings as good and evil, but are they? Does Nature interpret a lion killing an antelope as evil or Mother Theresa helping the sick as good? We as human beings label things, those things would still happen if we did not exist; antelope would still die and there would still be disease, they would be no more or less good or evil in objective terms.
The prevalent discourse at the moment is the Western mindset, the majority of humanity seeing the world in terms of duality, good and evil. Why is it ok for Christians to eat meat? The Bible clearly states 'That shall not kill', it doesn't draw a distinction between killing humans and any other creature, so why do most Christians not belive it evil to kill a cow for
food? Humanity fights against Nature, we try to define Nature and impose values and restrictions upon it.