Maybe she didn't want to shove religion and spirituality down the reader's throat, and also preach to them away from the message of "You choices make you who you are."
Ultimately, I found it refreshing that she didn't preach in the story, and it also will allow the readers to decide for themselves whether they want to go farther.
Or, I'm talking out my (ahem!) and don't know that I'm saying. (always possible)
I see your point, too, and I don’t think an overtly Christian message would have been appropriate to the story. I just think it’s inconsistent to have, for instance, celebrations of Christmas and Easter when (apparently) no character practices Christianity.