Yes, I thought of that too (although I think it's the maid, not the housekeeper).

I'm not quite sure whether the metaphor is meant to imply that Bunter's been subjected to so many hymn books in the past that he's been put off religion for life (as with the whisky causing the damage to the liver in the first place) or whether it's just an emphatic way of saying that Bunter is more likely to be repelled than attracted by someone who is seriously religious. I hadn't interpreted it to mean 'Bunter regards congregational hymn-singing as dangerously low church' - it would be a really odd choice of metaphor for that.