So they let their priests and followers know that the best way doctors can honor them is by ritualistically washing their hands with hot soapy water before they ply their trade
God: “there are millions of microscopic life forms they cause disease and infection if they get into open wounds” Human: “The world is full of invisible demons!?” God: “...you know what sure. If that’s what it takes to get you to wash your fuckin’ hands.”
In a Star Trek book, McCoy is time traveling and is helping with a wounded person. the local healer type is fussing and basically says that they’re afraid the disease demons will get into the wound, so Bones gives them a bottle of sterilizing solution and says it repels them.
it turns out later that the best medical college in the galaxy is in that system. Bones wonders if he accidentally caused a paradox and Spock tells him to not worry about it because it’s just going to make his head hurt.
Human: “The world is full of invisible demons!?”
God: “...you know what sure. If that’s what it takes to get you to wash your fuckin’ hands.”