I also found the book to be very humorous at times, in a satirical or sarcastic way, but I think the portrayal of Christianity is supposed to be very positive. I read it a long time ago, so I might misremember it, but the Catholic Church is what basically keeps all human knowledge from disappearing and is portrayed as its keepsake* (edit: I mean a keeper) of sorts, for next generations who will follow and will be able to utilise it. Also, and what frustrated me a lot reading the book, at the very end you get the pov of a priest (correct me, if I remember wrong), who observes people around him dying and suffering horribly painful, uncurable wounds but is very much against helping them, or even allowing them stopping their suffering, seeing their wish to end their lives as a great sin and basically enforcing the view that suffering in itself is necessary for salvation. This priest character read a lot like an author self-insert, at least to me it sounded like we were supposed to agree with his point of view. So while I enjoyed the book very much, and didn't mind the positive portrayal of the Church in the rest of the book, the end soured it a bit for me.