Med needing to be sober was neat, and looking back one of the 3 village women who had children was also an Ogre. So it's not a requirement for ogres to be continually drunk. It's just Med who is a barely functioning alcoholic.
I think this chapter is also the first one where the nuns did any fantasy clerical work, purifying an evil spirit. So that proves, or at least supports, the idea that they're pious and hard working enough to learn and cast clerical spells, even if they're deeply flawed. Before this it seemed like the church was a community boarding house for habitual petty criminals.