When I write, 'Dungeon World' I do not mean in this context just Dungeon World. I am referring to all roleplaying game settings and the way people roleplay the religions in their worlds.
In some settings and games it is pure mechanics. This amount of prayer provides this amount of spells, blessings etc. Although rules and special proficiencies and skills exist for many systems unless they directly affect play in some way they are often ignored. This is a mistake if you enjoy non-combat roleplaying as the marriage or funeral of a character is a wealth of opportunity for roleplaying.
Many settings assume a pseudo-medieval setting glossed over with modern sensibilities. For most groups that is fine but it is vanilla. Vanilla with an even 'blander' vanilla sauce. Those systems generally have a generic set of gods and godlets. Again, these godlings of various stripes have an area (or two or three) of specialization or interest but their primary function in the game is either as a mechanic for granting players their spells or as a McGuffin, "Fetch me the Undying Eye of the Stormy Skies unworthy mortals!"
No religion is paramount in power or strength over another. No religion is based off a real religious system (a notable exception to this was GURPS Fantasy that included Christianity, Judaism, and Islam in their Yrth setting, I have the first edition and it is an excellent source book).
This is preferred for many reasons not the least because modern sensibilities prefer that belief. No one wants to offend anyone (and rightly so) and many are afraid of bringing modern issues into what should be a fun and inclusive time. However, when you are only serving diet sodas no matter how many flavors you have there is nothing there but fizz and a little flavor.
Real religions are to fiction and the narrative of games heady stuff. There is a reason that the god of poetry was born of mead brewed by gods and giants. Real religions used in a game setting can lead to roleplaying and inspiration that is unmatched.
As I mentioned in my comment, if I may quote myself,
That is the standard for many. In my own games I tend towards the Poul Anderson, 'The Broken Sword'. Where all myths and creatures are real. I also follow the religious system for NPCs (PCs are free to follow whatever they like).In 'The Broken Sword' Christianity is a real and vital force opposing the older pagan world. It is pushing elves, dwarves, trolls, and other mythical creatures further and further from the world of men. It hasn't yet triumphed but it will. The wisest of the elves, trolls etc. see that and acknowledge it. They know their time is ending. For my players this does not create a dilemma. Player characters are important to me and have all the agency that the game can allow them. I also differ from the great Poul Anderson in that I allow whole races of mythical beings to choose to ally themselves with God. It preserves their place in the game and makes for in game conflict. So there are Christian elves and elves that in pride will choose to dwindle or go into nothingness. And that's okay, because it is a real conflict. Also, some are simply too steeped in evil to ever change. Which is good because who wants to try to convert every tribe of malignant dwerrow they meet?
It does pose players a choice. There is one God that can and will triumph in Europe (whether Allah does in Africa and West Asia is left open to speculation). Non-player character believers do not use spells to Apollo or Ra to stop a vampire, they use a cross or holy water. They use prayer for real benefit (if not always answered in the manner they would like or can see) and their society is bounded by these precepts.
While pagan areas exist and will for long centuries, for now Christianity is expanding. The old gods are still around and will answer player's requests (if it is within their powers) but even they know their time is coming.
This of course, is not the only way or even the best way to play roleplaying games. It is rare in that there is one True religion (in the areas where play takes place). There is a real God (amid the godlets, godlings and demigods) and by extension real evil. Yes, Satan will really answer you if it interests him (which is part of the plot of 'The Broken Sword').
So folks, how do you treat religion in your game? Are the gods just mechanical rules or does your cleric perform weddings, funerals and baptisms? Will Odin, Apollo, or Saint Michael answer your players' call for aide?
Let me know what you think in the comments. That way I can prove I am not crazy and just talking to myself.