If atheism and theism are worth discussing, then atheism is the view that God does not exist and theism is the view that God does exist.
At the end of the post, he queries, "So what's going on here? What am I missing?". I am only too happy to clarify this for Dr. Vallicella.
The proposition for the negative atheist would be, approximately, "There is no sound reasoning that leads to the conclusion God exists". This proposition certainly leads to a wealth of discussion over the topic, as theists and atheist discuss various arguments and why the reasoning is sound or not.
One of the most artificial assumptions in logic is the position that every statement needs to be assigned a value of true or false. Mathematicians,for the most part, are comfortable with this assumption because it is sufficient for mathematics. However, it is certainly not sufficient for reality. One of the features of skeptics is that we are comfortable saying "not enough evidence exists to make a decision". I see no reason to say God does not exist. I also see no reason to say God exists. So, I'm a "negative atheist". I'm not unsure about whether I believe in God, I don't believe in God, just like I don't believe in homeopathy, reiki, or theraputic touch.