Of course, the beginning is a little vague at the moment, too. I'm thinking that the main story-line will be about a religion that has dominated (not ruled, mind you) a small planet for millennia, but when a new prelate (as opposed to a pope, that's very important to the structure of the story) is chosen, a rival bishop (not cardinal, mind you) accuses the new prelate of fixing the selection process (mainly because he tried it and it didn't work). In an unexpectantly violent confrontation, the rival is excummunicated (is that the right word?) from the Order. Vowing revenge (or something sinister like that) the rival creates his own Order, a sect that worships God in completely different, far less pious ways than the original Order. Why they worship and honor the same God, their philosophy on how are completely different.
This is where the theme of White (the original Order) versus Black (the new Order) comes into play. You know how a prisum divides white-light into the colors of the rainbow, correct? The obvious conclusion is that if you blend all the colors of the rainbow, you would naturally get white-light. Still with me? But take those colors in paint and put them on an artist's palate. Blend them together and what do you get? Black.
So here's the tag-line that has got me started on this story: "Light divides, Dark unites."
So back to the story, a thousand years past before a new prelate needs to be selected. The theory is that the more enlightened you are, the more magic you learn/know, so it is apparent to the bishops that the prelate was a very enlightened man to have lived a thousand years, but much to their surprise, the rival has lived that long and shows-up at the "White" Order's "Vatican" to participate in the selection process for a new prelate.
I should probably explain how the selection process works. Each bishop, elected representatives from parrishes (not exactly the word I'm looking for) across the globe, place their left hand on the Holy Book of Armicus (the founder of the Order, and the first tome(?) of recorded history), and if the book begins to glow (or something like that) the person with his or her hand on the book at the time becomes the one chosen above all others: Prelate.
The main catalyst for the story is that after the rival and all the bishops put their hand on the book, it doesn't glow! Thus begins the search for the new prelate. I would say that chaos ensues, but that's not quite what I'm looking for.
Now that I've typed that all out, I've come to realize that the ending of the story should be the prelate being found, but who is the next question.
Again, your input is very important to me, so please let me know what you think, or what you'd like to know more about, or if you'd like to add any more ideas, please don't hesitate to comment.