I think KA's post explains it pretty well, but let me try a different approach.

When an atheist says, "there is no God," it is not meant to be taken as an epistemologically rigorous statement. This is the main difference in the thought process between an atheist and many theists. When a theist states that, "God exists," he can mean that to be an epistemologically rigorous statement since theists believe that a priori knowledge exists. In other words, they believe knowledge can come by means other than empiricism, such as revelation. The typical atheist is not willing to accept this. This epistemological difference is why atheism is more logical than that particular brand of (gnostic) theism. Your problem isn't with atheism's logic, which makes no assertions of certainty. Your problem is with our PR department, which has not yet corrected this colloquial misconception. That's what I was trying to point out in my previous post.

In your initial post you seemed to be insisting that the atheist's statement is epistemologically rigorous. My response was meant to point out that your statement was incorrect with respect to the vast majority of atheists. It is why I went off on the seemingly tangential discussion about definitions. The equivocation inherent to your definition of atheist, along with the other reasons I listed, is why I insist on using my definition.

With respect to a logically inconsistent theology I might claim to be an epistemologically rigorous gnostic atheist. With theologies that grossly contradict science, I believe they're incorrect in the same way I believe that I live in the United States. For a more generic theology I have only ever claimed agnostic atheism.