So what? Are you saying that this is a part of the definition of "atheist"?
They're separate statements; they don't have the power to "negate" each other.
Edit: I've kept thinking about what you're trying to say here, and I can't see it. Or at least, what I think is the most likely meaning is also obviously false, so I have a hard time assuming that you meant it that way.
It seems to me that you're implying that under certain conditions, it would be correct to say "both 'A' and 'B' are true, but because 'B' is true, we can't take 'A' as true on its own." Is this really what you're trying to say? If so, then you'll need to give some rationale for why you think this. If not, then you'll need to explain yourself more clearly.
... if you care about communicating whatever it is you're trying to communicate, anyhow.
No, it was defined here:
Hypothetically, if we asked someone "do you smoke?" and they responded with "what's smoking?", would you consider it wrong for me to call that person a non-smoker?
Edit: would you at least agree that ignosticism is a type of non-theism?