I saw a great deal of Christian significance, or more specifically, monotheistic significance.
I watched it with my 11yo son, and we had a good discussion about it afterwards. We came to the conclusion that the entire thing was an escape in the girls mind that was constructed through her religious upbringing and a need to turn from the brutal realities of the war around her. The final straw was losing her mother, knowing that a brutal and heartless man was going to envelope her and her brother.
I can kind of commiserate, as when my mother passed, there was no buffer between my abusive stepfather and me, and the abuse only escalated until we ran as far as we could. My brother and I were able to do it literally...she had to do it in her mind.
But then again, I did LSD in my teens, so what the heck do I know...