Here, this discussion, it is all about the quality and nature of such authority. Any time people are talking about whether God/Gods exist they have to deal with specific concepts. The first one put back on the shelf are those which are illogical, self-contradicting, don't reflect our understanding of the world.
Atheists and agnostics don't necessarily have a problem with there being a God or authority....but don't see any God-concepts as making sense or reflecting man's perceptions of reality.
You can only submit to something that is real to you to begin with, makes itself known or revealed to you. A God who wants belief and submission and considers it of prime importance, but doesn't make it happen skillfully and effectively, doesn't make sense to a lot of people. Especially with the difficult omni qualities so associated.
I believe Gods exist but are not obsessed with our belief and*don't want submission, personally. Makes sense to me on every level.