Now, before we get started, this has nothing to do with the M. Night Shyamalan movie. I know! I leave glasses of water around the house all the time too because of that one, but for right now, let's stay on topic.
Here is another great resource of really random things that those looking to write fantasy, or fiction, or really anything that might need a reference to religion of mysticism might find useful.
The Illustrated Signs & Symbols Sourcebook: An A to Z Compendium of Over 1000 Designs by Adele Nozedar (phew, that's a long title), is another good bedside book to keep handy.