Since no one burned my house down after the Tolkien post, I’m going out on a limb here and talk to you about using religion in your fantasy novels.
Generally speaking, when building worlds in fantasy novels, the religions of your world will be a reflection of the religions here on good old planet earth. So I’m going to offer a few suggestions – take them or leave them:
Know thy religion. If you’re basing your world’s religion on an existing faith thoroughly understand those beliefs. If all you have is superficial knowledge of a religion, it will show in your writing; at best you will look inexperienced, at worst, like an idiot.
Understand the core beliefs. If you are going to create a religion for your world that is based on Islam, I heartedly suggest you familiarize yourself with the Koran. Understand the meaning of the rituals in addition to the spiritual principles of the faith. There is a wealth of material written about different religions, avail yourself of it and do your research. If you are using folklore, understand the culture that produced the folklore.
Avoid stereotypes. Seriously. Muslims are not fanatical terrorists hell-bent on the subjugation of women; Jews aren’t moneylenders; Christians aren’t intolerant Bible thumpers; Wiccans aren’t green tea drinking vegans, etc. Even if you rename the religion in your novel, stereotypes will stand out and detract from your writing. Seriously.
Religions don’t kill. Adherents, who misinterpret and abuse sacred texts, manipulate events for money, power, or prestige, but the actual religion doesn’t go out and kill. Before you start flinging charges about any religion, make sure you understand the historical basis of these conflicts. Otherwise, (you guessed it) at best you will look inexperienced, at worst, like an idiot.
Treat all religions with respect. Whether you agree with a religion or not, respect it. This doesn’t mean you can’t poke fun or have a sense of humor about religion or certain beliefs, but don’t be snarky. You know the difference.
Don’t be malicious. Actually, this is a good rule of thumb for any type of writing, but especially with religion. Don’t write antagonistic stories; your point will become lost beneath your diatribe. Have someone with more moderate beliefs read your story and weed the rage out of your words. I worked for an attorney whose philosophy is: the most reasonable person in the room will win the argument. He is right.
World building is a difficult process; as a fantasy writer you are creating a whole social order, and you want it to be believable. You don’t have to be an expert in any religion, but do have a sound basis for your world’s religions. You want your characters to have depth and be a reflection of their society, then so should their religions.
A few articles to see:
If you’re looking for a checklist of questions to ask when world building, go to the SFWA blog where Fantasy Worldbuilding Questions by Patricia C. Wrede gives you a list of things to consider when worldbuilding. Religion and the Gods can be found under the heading Peoples and Customs.
Joe Wetzel at Inkwell Ideas has a great article with Worldbuilding: Fantasy Religion Design Guide, and a subsequent post, Worldbuilding: Fantasy Religion Design Example. These are really handy if your world works with a pantheon. These articles are about creating a gaming world, but the guidelines Wetzel sets out will work beautifully for the writer.
Alex Bledsoe shows you how to put it all together and make it work with his post At the Fiery Altar: Dragon Cult of Burn Me Deadly where he talks about his research for the dragon cult in Burn Me Deadly.