Just thought of something.
Most games can't make something like "Corruption" or other magical taint something really coherent and heavy -- this game is no exception, but I'm not seriously knocking that; it's a very hard thing to do and the game is ironically less about its title than its characters. So that in mind:
If the river cultists set up shop next door to Brother Sanders' workspace, you could have sex with the priestess and get the corruption removed on a whim.
Then I realized that's how many cultures irl have handled non-magical, plain-old sex for milennia, as well as other not-immoral-but-pretend-immoral behaviors.
If your main sexual partner was the priestess and you got Sanders' blessing after having sex with her regularly in order to keep your abstract "badness score" down, that would be the most realistic thing in the game.