I'm thinking--if I can find the time--I might do a few posts on fantasy world-building this week and some of the things that I consider when I'm world-building. This means I will be discussing the Magic Under Glass world (henceforth referred to, romantically, as "MUG world") and my Arestin world, which is an as-yet-unpublished world but I've been writing about it since I was 12 so I learned a lot about world-building from it.
Religion is just another aspect to consider when you're world-building, but it's one of the trickier ones because people can get annoyed about it. The most common religions in fantasy are, I think, belief in a pantheon of gods who may or may not be present as characters, or some kind of Goddess. I assume a goddess sounds more mystical than a god, and, well, you avoid that whole parallel with Judeo-Christian religion. Or, usually in Medieval-based fantasy, there is always the Evil Religion with Evil Priests and Oppressive Church in the Pocket of Evil King. Or you can just leave it out. In Harry Potter, for example, I always thought it was weird that Christmas was celebrated at Hogwarts but otherwise there was no mention of religion or religious holidays. I totally understood why she had it like that--goodness knows she got enough flak already--but it did make me wonder what people of different religions and beliefs would think of suddenly finding out they were a wizard, and what a fascinating story that would be to explore.
In the MUG world, I pretty much left religion out. Religion was an integral part of community life in the 19th century (it does come up in my Corsets and Clockwork story, in a casual sort of way); everyone pretty much went to church whether they really believed in it or not, and MUG is obviously set in an alternate 19th century, but then, do I make up an alternate Christianity for Hollin and Annalie? An alternate something for Nimira to have been raised with? What about fairies? Oh, the complications! Better not to mess with it.
In the Arestin stories, since I started writing them at 12 (Mists of Avalon phase ahoy) I went right for the whole goddess thing, so I could have a bunch of mystical women in robes and stuff. If you're reading a lot of 90s King Arthur retellings and listening to Loreena McKennit, what else would you come up with? There were two races in the world, the Goddess-worshipping Miralem and the Daramons who were of course all, "We will oppress your Goddess religion, rawr!" It was pretty typical at first. Over time, though, of course, things evolved and I worked out that the Daramons were quite different--their whole religious belief and how their moral choices were shaped wasn't even based around gods at all, but around reincarnation. I think if most of them believe in a God of some sort, it's more of a nebulous force of the universe than something you would worship. Daramons tend to believe in things that are more logical (at least, in their mind) than Miralem, and they don't generally pray or worship anything. They do tend to believe in karma, but I'm sure there is plenty of argument amongst them about who or what is deciding this karma, exactly.
This brings me to curse words and fantasy slang. I suspect that Daramon curse words are probably different than ours and some of them are probably based on these reincarnation beliefs, but how would you convey that without it sounding incredibly stupid? I don't feel that I could, especially since Arestin is a modern world with imported Earth culture and it would sound sooo jarring if Alfred was like, "By all the lives of my ancestors, the latest Arcade Fire album is awesome!" Or something. If it was an epic fantasy and he was like, "By the karmic power of the stars, this new broadsword is a dream!" that might sound a little better. (A little...) There is also the option of making up some word the characters can say all the time, but I don't like that either. For one thing, most languages have more than one word that is used all the time, but you don't want to throw in ten nonsense slang words, nor do you want to annoy with overuse of one. For another, what works in one language doesn't necessarily work in otherwise translated dialogue. Try throwing in Japanese curse words into English speech and making them sound right! The inflection is just all wrong.
Perhaps most importantly, the period you're trying to convey must be considered. Between the Sea and Sky takes place in a Regency-type world, so I felt I could completely get away with characters saying "Skies above!" or "Waters!" If it's replacing "Dear me!" or something, it sounds fine. If it's supposed to replace "Damn!", or worse, that might be...well, rather inadequate.
Oof. It's a lot to consider.
For more on the topic of religion in fantasy:
R. J. Anderson on religion in fantasy (I know I've seen another post from her on the topic but I can't find it anymore...)
Interview by Melodye Shore with Barry Deutsch, writer/illustrator of Hereville, which incorporates Orthodox Judaism and fantasy
Interview with Elizabeth Bunce at the Enchanted Inkpot where she talks about religious themes in "Starcrossed" and developing the gods in the book
Next time I might talk about developing magic systems. I already started blabbing about it in someone's blog comments yesterday so I think I can get a whole post about it...