The Greyhawk Grognard has made a post today talking about the role his faith (neo-paganism) plays in his games. It's a question that I've wrestled with over the years as well, so I thought I'd ramble about it a bit today; like many of my posts, this is completely off-the-cuff and being written in between getting work done, so you'll have to pardon the complete lack of structure (and likely the complete lack of a point as well).
My own faith is Messianic Judaism: That is, while I believe that Yeshua (Jesus) is the Messiah and the Son of God (though I've got different ways of expressing that than classical Trinitarianism), I don't believe that He came to establish a new religion called Christianity in place of the "old law" of Judaism. I don't have a problem with Christians in general, nor do I think they're going to hell because they treat Sunday as holy instead of the Sabbath, but I do get amused that they seem to think that Yeshua came to set me "free" from all of the feast days that I love and enjoy as a Jew. (How many Christians want to be set "free" from Christmas and Easter?)
As a Jew, I've a certain sympathy for the "evil church" trope that floats around fantasy literature and by extension, D&D. At the same time, I've enough historical background to know that that's an oversimplification: There were good popes who tried to protect the Jews and who issued papal bulls denouncing the synagogue-burners as well as those who put us in ghettos and initiated the Inquisitions. There were many individual Christians who have been friends of the Jews in every era, including during the Holocaust (as the garden of the Righteous Among the Nations in the Yad Vashem testifies).
Btw, while we're dispelling bad history, let's knock down a few mythical edifaces that the neo-pagan movement is trying to build: The Inquisitions were not going after Wiccans, because Wicca didn't exist at that point. They were targeted against Christian heretics and Jews--specifically, Jews who had converted to Christianity but still retained Jewish practices. Messianics, in other words. Moreover, pagans were not more open-minded and inclusive than Christians: Pagan Romans were feeding Christians to lions for the first three centuries of the faith's existence, and pagan Vikings and Saxons were raping, pillaging, and burning Christian villages before the northmen were converted by (mostly) peaceful Christian missionaries.
Nor are pagans more open-minded today, in my experience. The Greyhawk Grognard admits to characaturing the church in his games--which is his right, but one wonders if he would appreciate a campaign in which good faux-Christian clerics went around converting blood-drinking, violent pagans who were characatured as a bunch of unthinking imbeciles who worshiped the devil himself and fed the good clerics to lions for sport.
I've got some experience with this. My old home-brew world was based heavily on Europe of the 500s, including having fallen portions of the old empire but with a strong Byzantinesque empire still running in the east. I based it heavily off of Guy Gavriel Kay's Sailing to Sarantium (which, along with its sequel, should be required reading among gamers) and the movie Excalibur, specifically on Merlin's wistful line, "The One God drives out the many gods." I didn't take a personal stance on whether this was a good thing, and on the frontiers I had numerous cults rising around a resurgence in the belief in the old gods, which I based on actual Celtic and Teutonic beliefs. Several of my players, particularly those with a pagan or pagan-sympathetic worldview, didn't like it. Word got back to me that they thought that I was trying to force my own beliefs into the campaign and on them. (One wonders how they thought that an analogue to Eastern Orthodox Christian beliefs reflected my own, other than the monotheist part . . .)
Nevertheless, this was a major part of my decision to go with the Kingdoms of Kalamar setting; as a referee, I'm here to entertain (and be entertained, of course), and if a significant number of my players feel I've erred in how much of my personal beliefs I've brought into the world, then I'm willing to make adjustments for the good of the group. I don't hand out tracts at my table (or anywhere else, come to think of it). Nor is this a tract for my particular religion; rather, it's a rambling discourse on religion and clerics in D&D in general.
There is an implied assumption by many that D&D is inherantly polytheistic and pagan. Certainly, there is some truth to this in 2nd and 3rd Edition, where one's cleric's powers are dependent on which diety they worship, but there is no reason that this has to be so. As has been documented elsewhere, the original rules implied a kind of Christianity (with "crosses" being sold instead of "holy symbols," for example), with the quasi-Christian clerics going to battle against demons drawn straight out of Judeo-Christian lore. One could also easily cast clerics in the role of mystics in tune with "the cosmos," as the Grognard does, or men supernaturally empowered by pursuit of some great cause, as the Moldavy Basic rules do. I once toyed with the idea of clerics being attuned to artifacts called Foundation Stones, which offered protection to cities from the dangerous wilderness a few miles away from their walls.
Furthermore, many D&D and other fantasy worlds assume that there is in fact a Creator that the gods are subject to: The annotated Dragonlance Chronicles and Legends indicate that Weis and Hickman intended to explore the gods relationship with the All-Father someday (before this was derailed in the abominable Dragons of Summer Flame). The Forgotten Realms has Ao (though it is stated that he's not at the top of the chain either). Middle-earth has Iluvatar. Dennis McKiernan's novels have Adon. Jordan had the Creator--and no other true gods (unless one counts the Dark One).
Likewise, many real-world religions have some acknowledgement of the Creator, even if they emphasize the worship of lesser beings: Many Native Americans will speak of the Great Spirit, as did an African ex-shaman that I heard interviewed once. The pre-Confucian Chinese religion worshipped Shang-Ti, which translates as "Emperor of Heaven," and speak of Him in terms that could have been pulled straight out of Genesis and Isaiah. Even today, Oriental peoples will speak of "the will of Heaven"--a phrase not unknown in Traditional Judaism. Hinduism ultimately looks past its pantheon for the Brahman, and though there is less in common with HaShem in the Brahman than there is in Shang-Ti, nevertheless, the search for "the One" is still present. This was true of the pre-Christian Greek and Roman philosophers as well, who had become disgusted with their adolescent super-hero gods and had been seeking in fits and spurts the truly transcendent for some centuries before the world ever heard of Yeshua HaNetzerai.
The Bible itself, while consistantly insisting that there is only One Creator and One God for Israel, is frank that there are many lesser beings (angels, demons, etc) running around, many of which will provide miracles in return for worship and sacrifice. The issue was never whether these other "gods" have a real existence, but whether they are worthy of worship in place of or even alongside the Holy One.
Given the variety of real-world religions and the imaginations of the referees and players out there, there is absolutely no reason to be locked into a "there are many gods, but each cleric only worships one--and the Creator, if He exists, doesn't interfere" paradigm for fantasy gaming.
What if the gods were clustered into particular families or "political" groupings, and clerics represented these groups rather than specific individuals?
What if there is a single Creator, but He (or She, if you insist) interacts indirectly through servitor powers just like a human king is more likely to interact with a band of footloose adventurers through his agents instead of personally? And if that's the case, is that Creator neutral, or are some of the gods fallen from their original purpose? What if the Creator went "missing" (as in Kalamar)?
What if clerics are simply mystics whose source of power is unknown, and whether there is a God or gods is just as hotly debated in the campaign world as it is in ours?
What if clerics (and possibly magic-users) get their powers from attunement to some artifact or group of artifacts rather than from sentient beings? Could such artifacts be stolen, and if so, what would happen?
What if clerics serve the Law of the Cosmos, while magic-users get their powers from Chaos?
In all cases, it is necessary to think through the implications of one's implimentation of the cleric class in the way that it will shape your world--because it will shape your world.
There is a great tendency in D&D to treat the gods as Santa's elves, the harbringers of nifty toys--er, spells--and sources of quests, but who don't really affect the rest of the culture. This is hardly surprising, since most Americans treat God the same way, but the result is an impovershed world and many missed opportunities for not only adventure, but immersion.
Take the subject of holy days, for example. Most American Christians have exactly two religious holidays, Easter and Christmas, but don't understand the symbolism behind the trappings. Most campaigns never mention holy days unless there's a plot-specific reason to do so (and then the day in question tends to be just dropped haphazardly into the calendar to fit the timing of the adventure). But to most of the world, feastdays and holy days aren't matters of commercialism and pretty lights for pretty lights' sake, but symbolic recreations of history and legend, reconfirmation of ancient pacts and covenants, and prayers-in-action for future hopes. Failure to carry out these feasts were not just lost opportunities to eat, but were (and are) believed to actually bring down the wrath of the powers ones tribe was beholden to.
Passover is coming up, so I'll use that as a personal example: As a Jew, I keep the Passover Seder every year in remembrance of how God brought my people out of slavery in Egypt as a matter of real history. As a Messianic, I keep the Passover in remembrance of Messiah's sacrifice, which also took place on that day as a matter of real history. Every year, Passover serves as a re-confirmation of the covenants made between the Holy One and Israel as well as my own personal covenants. Every element of the Seder--every food we eat, every cup of wine we drink, every action we take and word we speak--is symbolically tied to these events and covenants; there is nothing that is done "just because."
All ancient cultures have similar rituals and feasts. Men didn't sacrifice animals just because, but as a symbolic way of giving a gift to one's patron diety and/or as a way of saying, "I know I've sinned; take this animal's life in my place." When aboriginal cultures put on masks and paint themselves, it's not for cosplay, but to act out the legends of their people and actively put on the personna of the gods to do so, letting the gods enter into them so that they became temporary incarnations of them. When the Celts put out food on Samhain, it wasn't as gifts to children, but to placate the ancestral spirits they believed roamed free on that night (a similar practice of offering food to ancestral shrines continues to this day in the Far East). Even activities that we in the modern world think of as being purely secular, like prostitution, had a religious meaning: The prostitutes were priests and priestesses, or temple servants at the least, and having sex with them was considered to be a ritual way of having sex with the gods.
The upshot of all of the above is that in every era except for the last two centuries, and even today in most places in the world, religion and culture cannot be separated. And if they can't be separated in the "real" world, where what magic there is is so subtle as to be completely missed by those who aren't looking for it, what chance is there for a secular society in a fantasy world where prayers seal up ghastly wounds and wizards hurl fireballs at their enemies?
I've previously written about how pleased I am at Kingdoms of Kalamar's approach to religion, giving us just enough details about the worship of its various gods to let us quickly construct some local flavor just by seeing who is worshipped thereabouts. The Player's Guide gives additional details about the holy texts each "church" uses. The trick is to insert these details in such a way as to interest players rather than have them rolling their eyes and tuning out. A quick write-up, no more than a few paragraphs (like in the linked post) may prove of interest; setting adventures on certain holy days and using them as backdrop is also a good idea (e.g., the PCs are commissioned by a town to bring them amber from the Urgoth Hills in preparation for the summer solstice ceremonies). Maybe there is a ceremony that nobody remembers the symbolism behind that some curious players might dig into (which I also gave an example of).
PCs should not be forced to participate in religious rituals--but they should know that other characters in the world do, and the better players will get right into the action for the fun of it.
In the end, a world with verifiable miracles should not be a world in which the gods exist only to give spells to clerics, like some etherial Santa Claus being asked for a pony. It should be a world in which the gods influence the culture--yet always in the background of the actual game action, or as hooks for future adventures.