I don’t think “atheist” or “agnostic” should be a character option, just because providing it is liable to give players unfamiliar with Forgotten Realms the wrong idea about the lore of the setting. “Faithless” might be more interesting, as it keeps to the lore, without suggesting “I just don’t know if Selûne exists” is something anyone but the most deluded, possibly insane, would ever think. I am sure someone in the Forgotten Realms thinks like that, but putting it in as a character option gives the impression it’s a position reasonable to hold. I support the idea of all characters being able to choose a god they are more dedicated to, without requiring it.