I was nauseated by Earl the angel for other reasons. But, let's take him as given. What is the appropriate response to somebody asking about the question of evil? If for whatever reason Earl doesn't want to give a straight answer--- he issues some mealy-mouthed statement about that not being what he's there for or some such--- a better-written angel would suggest that Grace should do her homework first! This seems such a consistent trope in "spiritual" shows; they treat problems of theology as if they are fresh and mysterious "big questions". Just like science fiction shows... and science journalism.
But, humans have actually put a lot of thought into these questions over the years. Obviously Grace is not asking about evil because she wants to know, but because she wants an excuse not to know or believe. But I still think a reasonable response from Earl is to point her at Theodicy on Wikipedia and have her come back when she's figured out what she doesn't like of the (many) answers already devised.