I have a long-standing beef with Clerics, but rather than focusing entirely on my issues with them I thought I would talk about instead why I think actual ancient polytheistic religious practices are so much more inspirational than what we currently have to work with.
Indiana Jones and Robert Langdon character types instantly came to my mind when reading the section “But What Do I Do About Clerics?”.
One solution I’d like to use more than in one-shots is moving the focus of divine from the person to the location. Keep a lot of the standard D&D-esque spells, but make them available in the local temple. This makes third-party healing and blessing possible, but not put on the shoulders of individuals, especially party members – it does remind me a bit of some early pixely video games, so maybe if the campaign is higher-powered, a fast travel network from the shrine of the Wandering God to other “unlocked” shrines would be appropriate.
For some special spells, certain times or more remote locations might be needed, which can lead to either a more traditional pilgrimage or exploring. Those locations then should be able to “store” the spell, with some sacred semi-relic, water from the holy fount etc.
Also, I’m all for a more pantheon-centered worship, but that’s a harder sell. What remains the cultural circles of a lot of “Westerners” is more the roles of the individual Greek / Roman etc. gods, than the day-to-day worship done back in the days, so the perspective isn’t as “group-focused”. Some novels do a bit better here, when it’s “The Goods of Light” most of the time, or the more focused pseudo-Jungian Game of Thrones deities, but when you get your average domain-oriented, 12-plus pantheons (“panthea”?), the collective vanishes too easily.
One thing Zzarchov Kowolski does in Neoclassical Geek Revival is that anyone with sufficient Piety can summon a Miracle on holy ground, but only someone with the Mystic class ability Thaumaturge can summon them outside of those sacred precincts. (Well, technically anyone can, but at a cost multiplier of 100, which means in practice no they can’t.) Theoretically, in a megadungeon campaign a party could find a secure area (either secred or guarder by an allied faction) and create a shrine there, allowing non-Mystic characters who are staying on the right side of that deity to spend piety for appropriate boons while the Thaumaturge saves their piety for combat use.
It’s not the thing I like most about NGR, but it’s on the list.
I find its much easier to worldbuild and treat religion well, if the system doesn’t reach its grubby little hands into something so foundational that its essentially telling you what the entire act of creation, the rules of physics and metaphysics, etc. is like in the game you are playing.
my personal theory is that all magic, be it “divine” or “arcane”, however you want to call it, should be in the form of a lil micro-fiction that allows players to basically break the rules, or take control of the fiction for a lil bit. its a lot easier to slightly modify a microfiction here and there to make it conform to the world, then it is to modify a whole “magic system”.
so yea, back to the OP, if you are focusing on working actual ancient polytheistic religious practices into something like D&D… its pretty much impossible without tearing the whole thing down.