A comparison of religion to legal systems is both only a sensible comparison to the three Abrahamic religions and incredibly useful for those three. (Other religions such as Buddhism are more starkly personal).

Essentially no Christian, Muslim, or Jew in any century takes the common scripture and reads it like an RPG manual for the game of life. Either they're laypersons who rely upon the guidance of experts, or they're the experts and they approach it with the advantage and bias of the years of study it took to become experts. And if those experts are wrong, there is always some authority to correct and rebuke their interpretation.

Ignoring the Protestant schism for a moment, this is exactly how the USA's legal system works. The body of written law and judicial interpretation are extremely complex and nobody relies only on the plain text of the law when they want to figure out how it affects them. Even the crazy sovereign citizens mostly rely on someone else's interpretation.

(And "sane" isn't really a helpful label here. It encourages atheists to think about Christians as if the latter are entirely unpredictable and unreasonable, when it's much more useful to think of us as mostly rational people who have a philosophical difference with you. More akin to the leftist/progressive/liberal/socialist discussion you can see on Lemmy than a MAGA/non-MAGA encounter.)