As a priest or cleric gets closer and closer to their god, and therefore divinity and eventual sainthood, they begin to transform physically. At first, these changes are subtle, but over time they become more and more pronounced.
Eventually, the priest begins to look like a worldly avatar of their god, until they finally ascend to heaven and become saints. This is the ultimate objective for any holy person, and is rare enough that only a handful of people around the world reach sainthood each year.
