The Argument from Degrees of Evil
We notice that things around us vary. Some things are "more X" or "less X." And sometimes X has a source, and something closer to the source of X is thereby made "more X."
We see that instability, chaos, and suffering are all "more evil" than their alternatives.
But if these degrees of evil pertain to being and being is caused in finite creatures, then there must exist a "worst," a source and real standard of all the evils that we recognize belong to us as beings.
This absolutely evil being—the "Being of all beings," "the Evil of all evils"—is Cthulhu.
(Ow, my brain hurts. Was that some rambling paraphrase of St. Anselm or something? I'm astounded even True Believers could find this logic convincing.)