I would recommend reading this before reading Elisabeth Leseur’s diary, as her personal writings are much more meaningful in the context provided by this book.
In Salt and Light, we read about the marriage and lives of Felix and Elisabeth, who loved each other deeply and enjoyed a happy marriage, but were separated by disparity of belief: Elisabeth a devout Catholic, Felix an ardent and vociferous atheist. After spending a considerable amount of energy on trying to dissuade Elisabeth of her beliefs, Felix discovers Elisabeth’s personal writings after her death which, gradually, lead him towards conversion and ultimately the priesthood.
Most of us will probably find Felix much more relatable than Elisabeth. His faith is faltering, he often finds himself questioning whether his faith is simply a reaction to grief, but over a period of reflection, study, and prayer he finds himself unable deny the truth of the faith his wife professed. By this point he is already almost 60, and so the impact it has on his bourgeois Parisian lifestyle, and the sacrifices he has to make in terms of material comforts and relationships, are significant.
It is heartening to see this example of reform after a life more or less built upon an atheistic and anticlerical spirit. Although a relatively small part of his life remained after conversion, Felix was able to bear much fruit by relinquishing his attachments to comfort and prestige and staying attuned to the voice of God.
My only criticism is that the book is very poorly translated - as a French speaker, I was very alert to the many instances of “franglais”. It could have done with a better editor.