Religion on my world works a whole lot like the religions of Earth. You can't truly "prove" the existance of divinity. The beliefs of anyone is completely up to their faith.
Gods don't walk the planet. Gods don't grant spells. Miracles are, well, miracles.
That being said, religion plays a huge role in the world (just like it does here). There are theocracies, holy men, zealots bent on bringing their vision of the faith to the world, etc. But there are also athiests, agnostics, and people searching for their place in the world.
What I am talking about here is adding a whole new religion, not a god to the existing pantheon. This religion would reject the entire pantheon even exists. Sounds like it could be fun.
Nightshade