None of the corruptions are evil! They're harmless below 20, and will unlock additional god-specific ending much later. In the meantime, getting above 20 will require you to make a conscious choice ingame. So don't worry about picking up a bit of incidental corruption, you can bang the succubi as much as you want without locking yourself into anything.
I will update the opening in a month or two, and we're starting to get lewd CGs and more custom backgrounds! Glad you're enjoying it so far!