"Is believing ghosts the same as believing in God?"

This seems to me to be the question at the heart of this book. Faith is obviously a large theme (as in all of Irving's work), but we have literal ghosts in Vargas's house, the women who appear and disappear, and (I think) the ghosts of Juan Diego's past that clearly still haunt him. These ghosts guide and shape his life, and there's a certain inevitability to them; Lupe knew (knows?) what's going to happen to him. What's the difference between believing in all of this and believing in God?