He really can. Merrily is such a wonderfully drawn character, but she isn't the only well written woman in the book.
So Merrily (who I keep seeing as Dawn French) has to deal with witches and weirdo Christians and a Jerry Springer type show. It is a really good book about faith and belief. Betty has it right - faith and religion are completely different.
I also really like Betty and Robin's relationship in this book. In part, because Robin while not prefect, really loves and cares for Betty. It's like Terry in The Detectorists when he is asked if the Lindy Hop is more important than protecting a site, and he says no, but Shelia (his wife) is. You melt and will forgive him pretty much anything.
Of course, the core relationship beside Merrily and her faith, is that between Merry and Jane. With Jane, Rickman has created a teen girl who is not annoying.
The mystery is pretty good and ties into domestic abuse issues, which was a good touch.