So I discovered something very interesting on my latest playthrough. I was trying to do a lovers run and regularly summon kitty while trying to reduce my corruption to zero. There are two events that I know reduce corruption which are saving the girl while taking a walk with Rio and not raping the nun when you turn invisible.
Turns out it is possible to reduce your corruption to below zero (negative 2). Not really sure what the implications of this are but according to the text, it looks like a new source of power entered your body. Possible angelic? Also it clearly came from an entity watching over the nun so hopefully we meet them soon