Continuing the series... it's fun (!) that a lot of people have been talking about this sort of thing around the blogs.
People have mentioned the idea of gods being something that are combatable and that take a direct role in human affairs (like the Greek gods). These aren't the sort of gods I'm talking about. If you kill Demeter, do no more crops grow? If you kill Apollo, is there no more music? If you kill Zeus, does the sky disappear (instant and total dissolution of the atmosphere and the exposure of the entire world to sudden depressurization and hard vaccuum would be one hell of a way to end a campaign...) If the answer to this sort of thing is "no," then we're not talking about the same thing.
Powerful entities calling themselves gods because they can aren't the sort of thing I'm talking about. I'm talking about entities that define the universe. Entities that actually regulate and define things and are the conscious embodiments or maybe creators of concepts like "the Sun," "Death," "War," "Fertility." Or maybe incorporeal consciousness that is on a greater level of existence, if not necessarily tied to a certain domain or portfolio. That's the lens through which to view my earlier posts on the subject.
I've already talked about not using "Good" and "Evil" in this setup. Priests may be specialized but they (and the people!) would worship the entire pantheon, and the gods themselves would be both good and evil (just as the rain can be both life-giving and terribly destructive).
But that's all good and well until you factor in clerical magic and paladins, as well as angels and demons and other religiously-inspired creatures.
Games with clerical magic by definition have changed the definition of faith. Belief is not something to be debated - the gods exist in some form. It's not an issue to allow clerics of various alignments under the same religious umbrella. Just take the mental and personality part out of the priestly requirements and separate what makes a character divinely favored from what the human religion requires.
In campaigns, being a spellcasting cleric should be different than being a priest anyway (and yeah, I'll state that as a universal truth), but if one's alignment (or whatever way you define morality in your game) is irrelevant to being a priest (or cleric), then each religion (or defined however you like, either involving one god or a pantheon) would have specific sets of rites and requirements for the granting of both a priestly station and the granting of clerical powers. Funny would be a situation where the human religion is clueless and is very far off from accepting the true divine will that creates spell-casting clerics.
Because clerical spells are granted by divine favor (and if they're not, you really need a good campaign explanation of why clerics and magic-users are different), it is conceivable that some recipients of clerical ability aren't even intentionally receiving them... or particularly cooperative with the idea! I'd stay away from that sort of thing with PC clerics though, because you're always one poisoned trap away from the possibility of somebody rolling up a new cleric for the group, and a succession of unwilling godly tools would just be silly.
Remember that religion, especially for those specially anointed, isn't just belief or devotion, but service, and if getting these powers were easy, everyone would do it. Who wouldn't want to cure diseases? Or curse an enemy... (say goodbye to restricting the reversed spells to only one alignment type under this way of things!)
Defining what a person needs to do to be a priest, and what they need to do to be a spell-casting cleric, can make for interesting campaign situations. What if the priestly orders of a certain god required vows of poverty and chastity, while the deity itself didn't care about such things, for one example? Religion doesn't always follow the will of the gods, even if it thinks it does. And as long as certain things are done correctly, the deity might not much care about the extra things the human worshippers invent in its name.
So OK, campaign religion can be as confused and vague as real-life religion, even when spells are on the line.
What about paladins? Or druids?
Druids only make sense in this setup if we're talking 2e clerics, with their specialized spell lists. (and good luck getting a player in the typical adventuring campaign to choose a God of Peace and Prosperity and its pile of not so immediately useful spells... :P :P :P) Otherwise, why the different powers? Certainly there can be verisimilitudinous (I love that word) explanations, but if normal clerics already have a pantheon to draw powers from, a reason why the druid would be different would have to be pretty darn good.
(My campaign world is more or less monotheistic and thus dodges this issue. I can say that clerics are worshippers of "All," while any druids are worshippers of the old pagan ways. Funny since the rules I've been running with this past year and a half don't have druids as part of the core rules!)
Paladins are difficult for me, since the idea of the class just seems to be a duplicate of the cleric concept (religious warrior) to begin with. But assuming you want to keep paladins in the mix as a concept - and I mean a real paladin, the "must be Lawful Good" shining beacon of everything noble and honorable, not the 'every god gets one' and 'nidalap' inversions (as we called them when I was a pre-teen... Gary would have been so proud!) - you need further explanations.
On one hand, all these explanations could tend to get really tedious, especially if none of this is any more than background flavor in your campaign. On the other hand, if you're going for a more involved world and not just dungeon-of-the-week, just the most basic beginnings of answers to all these questions will bring your world to life very quickly. In the real world, religious attitudes in many ways defines what a society looks like, so asking these questions first when starting a campaign may be a great method for world-building.
Again, my current game (BFRPG) doesn't have the paladin class, and with my campaign world being monotheistic, the context of the paladin's influences (King Arthur, Three Hearts and Three Lions, Charlemagne, and what have you) would cause no difficulty anyway. But in a polytheistic setting? I have no idea. Good grief, this whole thing about religion and gods is starting to sound like a campaign to stay the hell away from AD&D with its weird religious classes and too-fine alignment scheme. Keep it Basic and Law/Chaos, haha!
When it comes to demons and angels and all that... well, it's difficult to discuss them without resorting to cop-out non-answers. Clerical powers don't seem to work so much on good/evil as they do on extra-planar forces. Protection from Evil works just as well against an angel as a demon as an earth elemental.
So what's the definition of an angel or demon in a universe where the gods are themselves both good and evil? I'd say it's simply any extra-planar being. If it's helping you, it's an angel. If it's hurting you, it's a demon. Seriously, the only reason we think of demons and solars and modrons and xorns in such different manners is because the Monster Manual tells us to and the Players Handbook told us that demons come from the Abyss, elementals from their own set of planes, etc.
If you throw out standard AD&D cosmology (and why shouldn't you?), there's just "here" and "not here." Your average inhabitant of your game world isn't going to bother to differentiate a Type VI demon from a fire elemental from an efreet from a salamander. They're all demons, as would be any extra-planar creature, except those specific extra-planar creatures that an individual culture would be taught are "angels." If you're not Asian (or your campaign equivalent), then you're not likely to be too happy or calm about it when a Ki-Rin shows up, if you think angels look like handsome men with wings.
If we throw away the cosmology and just have an "other" place (or an infinite number of "other" places), then we can play thought games. Think of the variety of life on Earth. Then factor in that a normal campaign world probably assumes all of that... and more. Nothing has gone extinct (cavemen and dinosaurs show up in many campaign worlds, so what else didn't die out?). Plus there are all the additional sapient humanoids that aren't in the real world (elves, orcs, dwarves, etc etc), not to mention fantastic creatures like dragons and unicorns, all native to the campaign world. Add in the possibilities of extra-terrestrial life.
Now we can play with the idea that the infinite "other" realm, whether broken up into individual "planes" or "dimensions" or not, can be easily assumed to be as diverse as our own world. They don't have to be - an incredibly simple dimension works just as well for an alien environment - but it does create a stunningly simple explanation of why there would be so many weird things in so many forms. The possibilities are endless and they will each have their own tribes and characteristics.
An intruiging possibility is that there actually isn't anywhere else but our own dimension, and all the different forms of these extra-planar creatures are created entirely from the imaginations of the summoner. Forman the Summoner thinks he's summoning a flame-spewing demon, so that's what arrives. Herbert the Druid thinks he's summoning an earth spirit, so that's what pops up. Legends and folklore and ignorance that created fairytales in our world actually make the fictional creatures real in the campaign world.
Where do souls go after death? If gods exist, and if undead exist, and if there is reincarnation and resurrection and all that as the spell lists show, then there is definitely an in-game spirit and consciousness distinct from the biological life of a body. You don't have to define this, and to recreate a trip to Hades or recreating the plot from Erik the Viking doesn't mean that where you see the dead is actually where the dead go (a mortal going to "Valhalla" just might be questing to find one hell of a seance parlor), but to definitively answer this is to make players think they can get around using magic to raise the dead... but it's common in fiction and folklore for souls to go to the places assigned by certain rituals, so being sacrificed becomes much more horrible than the physical atrocity and proper last rites become crucial...
If we're rethinking D&D cosmology, what of planar travel? Making these changes will alter how many spells work. Contact Other Plane certainly needs reworking. What of the nature of the ethereal and astral planes? The whole assumption of inner and outer planes would need to change. My thoughts?
For Contact Other Plane, change the percentages to be based on a magic-user's combined level and intelligence, rather than "planes removed." Make the ethereal and astral planes one and the same, or maybe the astral plane becomes a dream-realm, or something, but either way, they do not become gateways to further planes and should be connected to our world. Since these methods won't be "connecting flights" to further planes, you just need to add a planar travel spell to the spell lists, perhaps making each individual destination dimension its own spell if you don't want things to get too far-fetched.
And none of this has to eliminate any previous adventure possibilities. You want to play Q1? Instead of Lolth living on whatever plane of the abyss, she's just got her own subdimension, not intrinsically connected to any others except for the types of gates shown in the adventure itself. The drow clerics may worship Lolth and think they're getting clerical spells from her, but Lolth being a crafty demon has simply made the divine rites of some other truly divine power part of her own worship, so the drow clerics gain their spells and worship Lolth and never realize their power is actually coming from elsewhere. (Or they might realize, and that's why certain houses are now worshipping something else...)
So there it is. I hope this long post is a bit more coherent than the last one, but aside from any discussion stemming from the posts themselves, I think I'm done with the subject for a good long while. Maybe. :D