Update on NaNoWriMo #13: Good vs Evil in Urban Fantasy

I'm still thinking of the larger context of my novel, the worldbuilding necessary to sustain a larger series. I had the idea for a holiday fantasy novel for a while before I found the courage to write one, because I was aware of a problem. I realized if I wrote a holiday novel, I'd have to figure out a theory of good vs evil in a context that was familiar (because I was using real holidays) and yet unique (because I'm telling this story). Also, I wanted to write fantasy, not theology, but if...