Absolutely agree. I always found it quite bonkers that any teenage boy would care at all about what happened in the Church (and I'm speaking as a brought-up-Catholic teenager) but I loved that religion was being discussed in the books. What other childrens' or teenagers' books mentioned it at all? Much older, classic books assume everyone is Christian and lay on a Christian message in a fairly heavy-handed way. But I can't think of another author who allows the characters to discuss religion, including the viewpoints of the sceptical but intelligently curious, the brought-up-faithful-but-wavering, and the unfashionably committed.
I wonder if Patrick's obsession with the traditional forms of the Mass is precisely because he is losing his faith.