I think atheism is "theism is false". It is a necessary condition of atheism to be "not theism", but it's not sufficient in my view. Just like it's a necessary condition of negative numbers to be "not positive", but it's not sufficient since the number 0 is "not positive", and yet it's still not a negative number.
"The reason things will never get better is because people keep electing these rich cocksuckers who don't give a shit about you."
-George Carlin
-George Carlin