I cannot contribute much as an atheist because, like Edgy, I am a Deist. There are various forms of Deism as Theism; for the most part modern Deists believe there is no separate God entity. Rather all of creation is the God entity.
If I were to make a parallel answer, as a Deist, I came here to attempt to understand the belief structures of Theists. Not only their belief structures; why they believe what they believe, why they are so sure of their particular brand of Theism, why so many Theists in the world take the belief of a God of love and pervert into personal hate, and so on.
Seems to me an atheist might be interested in being here for similar reasons.
Unitarians include atheists in their churches...folks of all faiths.
I have a friend who has been at UU seminary...traveling the world learning other religions...The Unitarians are another group in and of itself. I know a few Unitarians, and their beliefs are kind of strange to me. However I found that they were members of an obscure branch, yet call themselves Unitarian Universalists