Atheists argue that there is no god that is either good or evil
Depends on the flavor of atheist, in my experience. I'm an atheist, but I've never argued that there is no god, because how the hell would I know that?
Some use the term "agnostic atheist" to describe this kind of atheist, but I'm of the mind that it doesn't need the qualifier "agnostic" since atheism is simply lacking a faith in any god, in contrast to antitheism, which is the active belief that there is no god. Antitheism is, ironically, a belief system rather than the lack of one.
Perhaps my understanding of the term "antitheism" is incorrect. Though I checked Wikipedia before making my comment. Wikipedia's first paragraph says:
Given the latter definition, I think I used it appropriately. Though it's apparently a spectrum, similar to atheism/agnosticism.
I stand by my assertion that the term "atheist" doesn't need the "agnostic" qualifier to specify that a given person isn't asserting that there is no god. In my experience, people incorrectly assume all atheists are de-facto antitheists and believe, actively, that there is no god, which just isn't the case. But the additional clarification by adding "agnostic" is certainly helpful in terms of clarity; I can't argue against that.