First of all, I don't know how you want to implement them, it could be that you make something fantastic out of it. But for the most games I've played that had gods and/or religion made it to complex yet very important to have.
My aversion of this could be a bias of me because I can't really support my statement. It's just a feeling.
But then again, I don't know your view on these elements :)
My current thoughts for the feature are: a pantheon of 5 or so gods and godesses, each with a different area of interest. The player can build temples to curry favor with the gods. The more favor with the god, the more benefit the god gives. The player can also invoke the god for miracles.
As an example: Akkan the Skyfather is the god of the skies, and father of the pantheon. Earning favor with him provides favorable weather (occasional light rains, fewer storms). He can be asked to create a storm, with lighting bolts striking enemies.
