The tenets of a real-world religion can interact... oddly with fantasy or futuristic settings. In the simplest form of this trope, the setting makes religiously forbidden things harder to avoid, or mandatory things harder to do. Maybe it's impossible for Jewish vampires to keep kosher without starving. A group of Muslims on a Generation Ship is likely to have trouble making a pilgrimage to Mecca. (It's also possible in principle for a setting to make religion easier, but that's less likely to happen as it fails to follow the Rule of Drama.) Examples of Fantastic Religious Weirdness include: