Thank you for your two cents! Much appreciated. And you're so right that there is SPN canon evidence by way of The French Mistake to suggest that Supernatural takes place in an AU that is not our world.

As a non-religious person I've certainly never thought that Show was portraying an accurate version of Christianity! I see the actions of the angels as somewhat allegorical. Show portrayed some of those who should be divine as having lost their way and started doing bad things (ie Zachariah and his ilk), and this is something that has happened in some Churches--some of those who should've been faith leaders losing their way and doing bad things. So for institutions of faith (portrayed here as Heaven) to be weeding out the bad apples, to be in upheaval and trying to understand themselves in a modern era, as well as having to deal with the fact that so many people have lost faith, that seems relevant to our world. And I guess...free will, destiny and morality are universal themes. People will engage with those ideas differently depending on their background, but I think those themes speak to everyone in some way, which is why everyone from an atheist to a Bishop can engage with the Show! :)