The alethiometer has clearly been tested in its creation and so while Lyra does not put it through much testing, she puts it through as much testing as one would put a compass through. She uses it to guide her to some person or place and it delivers her there successfully every time.

I also think the criticism that the alethiometer doesn’t distinguish between murder and manslaughter is a bit overly pedantic. Not least since the correct term to use when someone is killed in a fight is highly debatable.

“And as a third pitfall, Lord Asriel’s arrogance, hunger for power and thirst for immortality, and his willingness to kill the innocent to get what he wanted, represented the worst traditional depiction of atheism.”

But there are no atheists in that book! They exist in a world where God exists. What’s more you are not supposed to like Lord Asriel at the end of “Northern Lights”. He does the one thing we’ve been told throughout the story is absolutely abhorrent, the separating of a child from their daemon – their source of creativity and individuality. Naturally the fact that he does so in order to gain power is no better than doing so in order to seek control or to ‘free’ children from sin. Did you get through the whole trilogy without realising that Lord Asriel was a bad person?

But yeah, the third book definitely drops the ball. After “The Subtle Knife” (my personal favourite of the trilogy) the third book (and the longest too, my goodness) was a big letdown.

Since you’ve already mentioned Pratchett, I would recommend some graphic novels. Garth Ennis’ “Preacher” is a very awesome comic series about a Texan preacher who becomes possessed by a power which could potentially kill God, while God Himself has gone into hiding. I also like his somewhat more recent “Chronicles of Wormwood” about the son of Satan who is rebelling against his father.

Of course, HP Lovecraft is a writer who writes about a supernatural realm in which he does not believe in order to horrify the audience. For him gods are terrifying. Of the stories I’ve read so far I think “From Beyond” is probably my favourite and it’s available online if you look.

If you want a writer who leaves the supernatural out of it, Iain Banks is an atheist and his book “Whit” is an interesting story about a cult member seeing the wider world outside of their commune for the first time.