Religion in fantasy worlds eh? What's the deal with that?
In fantasy worlds you generally don't have the fun of the question 'What if?' when it comes to gods. They're right there, walking down the street, inconveniencing people with plagues of frogs and generally acting like... well... player characters would if they had that much power - or like Discworld Gods with slightly more decorum and a lot more self importance.
There's no difficult questions, demons are real, gods interfere in people's lives, devotion gets you magic and so on.
On the flipside most SF games completely ignore the whole thing entirely save for primitive tribes worshipping idols that just happen to be Hyperspace Q-Modulator crystals or something.
Doesn't that strike anyone else as a pity, or odd (from a story point of view?).
In the fantasy games you don't have the question 'Are there gods' its not a matter of faith, its a matter of choice. Which god do you want to piss off the least, which offers the best benefits. It's more like competing brands in a supermarket and acts of faith are not required.
In the SF games you don't, generally, have people acting through religious motivation and yet SF is usually the 'now' projected forward. Oh, there are exceptions of course, SF covers a very broad base, but you don't see that much of it considering.
One of the better ideas I think I've come up with in gaming was the Royomuertivan society in Cloak of Steel. An atheistic society, a breakaway group, entirely invested in the here and now (The world has no proof of gods) and relentlessly rational and decadant. They pursue a life of luxury and immortality through Necromancy, a magical science that most others regard as evil and corrupting but which the Muertivans regard as a good use of dead bodies and a good supply of uncomplaining servants. Their ancestor spirits are bound into skulls and stored in a great 'chamber of ancestors' where they discuss and formulate policy for the kingdom. A land ruled by and supported by its dead - very practical given the gameworld.
I find that whole idea fascinating, breaking taboos in fiction and examining viewpoints, playing with them. Just wish I could use the same idea somewhere else or make CoS more popular.