First off, D&D is not evil or Satanic. I don't play RPGs but there's nothing evil about them, science fiction, or fantasy novels.
Second, Tolkien said LotR was not allegory, true, but he did say it was applicable. (This is taken from the Introduction.)
Third, good is Good, bad is Evil, and never the twain shall meet... Tolkien shows clearly what evil does, and why it must be opposed. There's plenty of other stuff but I think I'll leave some for the other Tolkiendil (a possible name for 'lovers of Tolkien'?) who are here!
Well, Gary Gygax's modules were. Oh, wait, maybe I'm just confusing sadistic with evil. ;-)