If you saw what appeared to be a spiritual entity of some kind (angel, demon, ghost) what would you do? Would you assume that you are delusional or mentally ill? Would you tell anyone? If you don't currently believe in such entities, would it change your perspective or would you discount your personal experience as something else?
What if it happened to you more than once? I, for one, have not seen anything like this; but many, many people have claimed to witness supernatural occurences. Therefore, I feel like I have to at least consider the possibility that they're not ALL crazy.