I distinctly remember reading these as a kid, although they do run into each other at times. There was also an animated TV show that I hardly remember anymore.
I can’t recall which book it was, but one has a villain who wears an animal skull on his head who's killed by being clubbed, which causes the teeth to penetrate his brain. Good stuff, that.
Also, another where a character thinks about how foxes and weasels cannot be trusted no matter what, tries to trust them because others do, and then is right.
Edit to add: if you like this series, do yourself a favor and read the Duncton series (2 trilogys) which are about moles in the English country side. It's also about religious corruption.
The very first book is about how a dark age settles on Duncton, leading to horrible crimes being committed; the main character keeps his faith however and manages to survive. Next 2 are about a rival religion, started by one who fled Duncton in the first, that rises up and takes over moledom. This leads to mass killings, torture, ect. It's grim, and only the coming of the "stone mole" can save society.
Second trilogy follows one character in her quest to write the Book of Silence, which is a book all about death and the reality that all which happens will one day be forgotten by all. It has the return of the death cult religion under a new name and gets even darker.
Amazing series but it's long and weirdly hard to track down in full.