Thank you for the warning. I imprinted hard and weirdly on this book in childhood, but I haven't re-read it in years.

The idea of having a secret tunnel in one's attic, and of magic rings that would take one from world to world -- it was very appealing. (It took me a decade or two to realize that the secret tunnel in the attic was because the houses adjoined. I assumed that they had a separated house with a magic tunnel.) I'm not sure I actually paid attention to the deeper plot, and I know I missed all the Christian allegory. Who wants plot when you can have magic rings?