From what a friend who is an avid reader has told me, apparently the being they kill at the end of the story *possible spoilers follow* is not actually ‘God’, but a old, decrepit angelic-level being pretending to be God. Apparently ‘God’ either does not exist or is apathetically off ‘somewhere else’, letting the world do as it pleases. So I really don’t know what to think of it - I actually haven’t heard anyone else who has a neutral standpoint (ie not atheist or Christian who have a reason to like or dislike the books before reading them) say anything about it other than lauding the writing quality and style.
It's a no-holds-barred atheistic attack on religion.