The thought I had the other day was also partly a reaction to DMs eliminating Clerics from their games. Is there another way to do it that’s interesting and just as extreme? Sure – everyone is a Cleric.
Earthdawn gave everyone magic because the setting is magic-rich (in a way) so there’s no such thing as “just a Fighter” for a PC. There are always going to be non-magical scrubs out there.
You’d say that the typical healer-Cleric worships a god of peace or health, so those are the abilities he gets. If your character worships a god of burglary he’d have Climb Walls, Open Locks, Find/Remove Traps, etc. A Cleric of the wilderness might be more like a Druid or more like a Ranger depending on which god it is. M-U and Cleric spell lists would need to get chopped up like the 2E Cleric spheres. Actually, you could probably get by without doing any work by just forcing everyone to play a Specialist Priest out of the Faiths & Avatars and similar books (I recall at least two others).
Even Conan swore to Crom. Fighters get their supernatural toughness and slaying prowess from a god of war, not just because they’re “experienced” mortals. A demigod like Hercules would benefit directly from his immortal bloodline but would also be able to gain levels. No more complaining that a 10th level Fighter has more HP than a dragon.
A 0-level human could start earning XP if he proved himself worthy through great deeds – like how Philotomy’s play report of the module I4 (which is down at the moment) had a caravan guard who rolled nice in combat for a while got promoted to Level 1 Fighter. Which brings up a great starting question for a 1st level PC’s player: what did you do that was so cool you were able to hit 1st level?
Not everyone has to get spells – but why not? Give Thieves some low-level illusions, Invisibility, Silence 15′ radius, etc. But give it to them at higher level like Rangers and Paladins do, and lower caster level and spell capacity. That way he defaults to his skills but he can bust out something special for the really difficult parts.
Why would an adventuring party of holy men and women of different faiths band together?
1: The gods aren’t so shitty to each other as we might expect, and gods of similar alignment are fine hanging out, havin’ a brew, watchin’ the game.
2: Clerics don’t antagonize each other trying to get conversions (a negative method) but try to outdo each other in great works and achievements (a positive method).
3: All the human/demihuman gods, even if their alignments differ, are still opposed by alien and especially nasty gods like those of the humanoids. Moradin might want the best of everything for his Dwarven people, but he’s going to be happy to work with an Elf god to fight against Orc gods – and especially against a god worshipped by Underdark slimes, Githyanki, Mind Flayers, etc. There’s a greater threat out there, so it makes sense for the PCs to work together.
Carousing can be handled as usual or maybe just for donations.
Motivation to adventure is a little easier.
Given enough deities, you could get a mix of abilities without alignment problems. For example, a 1st edition Monk is able to do a lot of what a Thief can, so a party could do without the Cleric of Burglary. If you want a scout, you could get a Cleric of Woodcraft (Ranger abilities) or a Cleric of Secrets (divination, invisibility), or of Illusions, or Psionics.
Not sure whether this changes much besides giving a justification for superhuman abilities in high-level characters. It is nice to have secular character options. But you know how this works; it might be cool for someone’s game.