Really it's worth remembering that the supposedly well-ordered pantheons of European and Asian theologies all were in practice probably a lot more like the chaotic deities of Haiti which Hurston chronicles so well. What strengthens people's belief isn't really the intellectual coherence of their religious practice, it is how well it works to channel communal and social experiences which are difficult to deal with otherwise, and to give a sense of reassurance that the grottiness of this world may not be all that there is. Hurston conveys the Haitian experience of religion and belief very well.
I have to again complain about the presentation of the P.S. edition. The table of contents promises a foreword; there is none. There is an afterword by Henry Louis Gates, and then an after-afterword by Ishmael Reed which I suspect is the foreword misplaced. But the publishers really ought to have ensured that the contents page actually coincided with what is in the book.