Is the earring exclusively religion-oriented, like a crucifix, or is it more generally cultural? Even if it was generally associated with Bajoran Prophet worship, it doesn't follow that wearing the symbol means she's a follower of the religion. Besides, she wore the earring on the opposite ear of all other Bajorans. Surely that indicates something
about her belief, ranging from "I'm aware of all religious doctrine and beliefs, but choose to not participate" all the way to possibly meaning "I despise all religion and only wear the earring to keep the vedeks from squeezing my ear".