TrippyHippy
Hero
Let's not get classes and occupations confused. A character class is a set of character-rules constraints and options, sometimes with a theme. An occupation is something that your character does in-game to get by in the world. I'm no expert on RuneQuests's cultures, professions, and cults, but just keep in mind that this thread is only about the character-rules end of the class-occupation spectrum.
Classes are a powerful tool for imbuing a sense of character in a player. They shouldn't have anything to do with a character's in-game experience (of society), because classes are a metagame feature. Now, that's not to say that a character's class and occupation can't coincide. Just that they're two different things.
They don't have to be - indeed, they don't have to be metagame, either.
Being a Cleric, or example, does indeed inform us of the characters place in society - they are a member of a clergy (be that of a church or cult or whatever). The classic four D&D classes loosely correspond to medieval societal classes too (Those who fight, those who work, those who pray and wizards being something of a fantasy archetype on top). I certainly don't see why they shouldn't have anything to do with a character's in game experience of society at all. Classes, careers, clans, houses, cults and cultures all provide information for character identity - and that identity is integral to the society it is part of.