“I contend we are both atheists, I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours.”
“We are all atheists, some of us just believe in fewer gods than others.”
The above two quotes (attributed to Stephen F. Roberts according to this web site), despite the frequency with which they are quoted by atheists, are not even good sound bites and much less are they good arguments for atheism.
First, atheism has nothing to do with the number of gods one disbelieves in; rather it is belief that no God or gods exist. To equate theistic belief with atheism is a logical absurdity. Just as a person cannot both believe in God and not believe in God at the same time, one cannot claim that a worldview that affirms the existence of God is equivalent to its antithesis.
Second, to not believe in God because there are any number of wrong concepts about what or who God is, is as silly as believing that there is not a right answer to the equation 1+1 because there happens to be an infinite set of wrong answers. Just as 1+1 has only one right answer, the question of the existence of God has only one right answer.
When we see a building, we know that there was a builder; when we see a painting we know that there was a painter; and when we see creation, we know that there was a Creator. Unlike basic math which cannot be proven, the proof of the existence of God is everywhere and all around us, all we need are eyes that see and a brain that works to prove it.