Atheism is typically defined as the disbelief in the existence of God. However, many (if not most) atheists are inclined to argue that "God" is a meaningless term. If you are an atheist who has made such an argument, then I would argue that your "atheism" is meaningless because you apparently do not understand what exactly you are disbelieving.
A person can't possibly believe in what they can't conceive, so I don't see what the issue is.
The line between gods and other entities IS so fuzzy as to be meaningless. Yes, this might be a problem for an atheist who says "I don't believe in any gods... but I do believe in angels, ghosts, and fairies" - but I've never met an atheist like that. A person who doesn't believe in gods, angels, ghosts, or fairies doesn't really need to care about whether a tree nymph, for instance, should be classified as a god or a fairy.
... but theists often do (or should) have to worry about these things.For instance, what makes an angel not a god? If Mercury, the divine messenger of the Roman religion, is a god, why isn't Gabriel, the divine messenger of the Christian religion, also a god?
The only way I've been able to sort out questions like this is by defining the category "gods" in terms of a list of beings that are described as gods: Apollo is a god; Superman isn't. Mercury is a god; Gabriel isn't. Hades is a god; Satan isn't. Why? I have no idea. I can't come up with any objective criteria to define "god" that works across religions.
... but it sounds like you have these criteria. Care to share?