This story is about the inner turmoil of suffering. Lucy Snowe believes she is a sort of cosmic target, so she develops artifical ways of coping - turning off her emotions, hopes, everything that is most human in her - in order to avoid disappointment. She wants to turn herself into an automaton (Jane Eyre's worst fear).
M. Emanuel (aptly named) is a redemptive figure. He begins by drawing out the real Lucy. He discovers what she really thinks and feels. Then he provides for her beyond her highest expectations.
The religious element in this story is unavoidable. Lucy's struggle is with God. Why does He weave a life of suffering for her? The counterargument to her accusation is that He provides for her in miraculous ways - through the priest, the Brettons, the bookseller, and M. Emanuel.
You cannot read this story without wanting to know more about Charlotte Bronte. The psychological portrait of Lucy Snowe is true to life on an extraordinarily deep level. Lucy's emotional landscape is described in vivid images that merge with the physical settings of the story.