It's always interesting to see works of science fiction or fantasy where their lore is so well developed that you could consistently practice their in-universe religion and have enough material to go on to cover almost any situation. The lore of the Elder Scrolls is the most obvious example in video games, but not for nothing did "Jedi" show up as a statistically meaningful count in the Australian census when Aussies were asked their religious affiliation (and yes, I know most of them did it as a joke, but the core of the premise is still sound.)
L. Ron Hubbard cynically exploited what was essentially a bet with one of his friends to create something indisputably Neutral Evil, but the Imperial Cult from the Elder Scrolls is solidly Lawful Good and the various daedric princes range from Lawful Good (Azura) to Chaotic Evil (Mehrunes Dagon, as seen in Oblivion) and every possible alignment in between (yes, I adore Sheogorath, how'd you know?)
Then there are religions that don't rely on gods—-the Ultima series from Quest of the Avatar on, for example. There are well-developed corrupt churches, especially in Japanese games, which tend to be harshly anti-Christian (the Glabados Church in the original Final Fantasy Tactics, not to mention the Kefka-as-Jesus theory in Final Fantasy VI.)
A long time ago, I remarked to a Christian who insisted that there was only capital-G God that "if that's the case, then why bother with the First Commandment? 'Thou shalt have no other gods before me' only logically works if there _are_ other gods to put first, and I choose to do so personally because your god is evil."
Way I see it, there's not even anything logically inconsistent with recognizing an obviously fictional religion as legitimate, since the Elder Scrolls pantheon actually fits my Grand Overarching Theory of Theology (mein GOTT!)—-that the Old Gods are interpreted through the prisms of the cultures who worship them, and Tamrielic culture, in its own lore, is internally consistent. For the people on screen, and I'm sure this was entirely unintentional on the part of the writers except where it was explicitly referential to a real-world cultural touchstone—-Skyrim is full of this, they belong to the brotherhood of the True Gods in the "real world."
Whether this enhances or cheapens the real-world idea of gods is in the eye of the beholder, but I think it speaks to Cicero's original remark in Roman times: "Nature has imprinted on the minds of all the idea of God." (go ahead and read that in Leonard Nimoy's voice, you know you want to.)
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