Why is there so much evil in the world? Why is there so much suffering? While these two questions seem to be asking the same thing, they are really two different questions. This is because the word “evil” makes a value judgment word, while “suffering” (or “pain”) is essentially value-neutral.
I recently accompanied my mother to see her doctor. My mother suffers with the pain of arthritis. The doctor pointed to the “smiley scale” on the wall and asked, “How much pain are you experiencing?” On a scale of 1 to 5, what is your level of pain? My mother said, a “2” or a “3.”
My mother experiences ongoing pain from her arthritis. Is this pain “evil?” Is my mother’s pain “unjust” or “unfair?” To ask questions like this is to ask for a value judgment. Value judgments only make sense if measured against non-subjective moral standards with which most agree; viz., “goodness,” “justice,” and “fairness.” In other words, what sense would it make to ask if something was evil if there was no such thing as good? Further, if by "good" we meant only subjective ideas of good then "evil" would fluctuate and vary with a particular person's personal idea of "good."
Non-subjective moral standards are, by definition, objective moral standards. Objective moral standards are moral standards that exist outside of human subjectivity. I believe objective moral standards exist, and find their locus of meaning in the nature of God.
But note this. A person who believes there is no God-as-Locus-of-Moral-Standards cannot really use the word “evil” in a question like, “Why is there so much evil in this world?” This is precisely because the atheist believes there are no common objective moral values to which all persons ultimately appeal. All the atheist can really say is something like: “Suffering exists.” And, “I don’t like suffering.” But, on atheism, one cannot universally refer to suffering as “evil.” This makes no sense outside of theism.