Artemesia is just sore from his days back in the church and then getting kicked out. Religion is very important in Dwilight and I stand by what I said before, it is another way to interact and build the story in Dwilight. Many of the people who are not in religion probably are putting some RL slant on why they don't join a religion.
Atheism is lack of belief in god...The Christian god does not exist in BM. Lack of belief in the Bloodstars would be Antihypernymastrum or something goofy like that.
