I hear ya . . .most often he writes about the scariness of the human spirit.
My own mother used to be one of "those" religious people who never understood why I was such a SK fan & how I could read stuff like that, etc. Decades later (and within this past year), I convinced her to read Bag of Bones. SHE LOVED IT!! Now, she wants to read 11/22/63!! =D
Two excellent choices! Also, if she likes mysteries, Joyland.