I think, unlike Skyrim, having mods play the role of gods on the pantheon would give more weight to your "religion." It's not just about you picking which buff you want, but instead about supplication. You can choose to worship at the alter of Angyles to gain the protection of the Queen of Dragons, but maybe she rejects you? Or maybe the blessings of Kainzo are powerful but short lived and only given to the small few that currently carry his favor.
I can understand the concerns about OPness, but open world PVP isn't really about things being "fair". Numbers, gear, and surprise matter a lot and often matter more than skill. The only time it really matters IMHO is during a tourny, in which case all religious buffs could be turned off.
Oh and I agree that the "gods" should be concerned with your class. Particularly classes that communicate a strong alignment like Paladin or Dreadknight. but then again, who am I to suggest what the gods should be concerned with?
May Apherdite keep you from harm, and may LightningCake spare you from his cakey wrath.