Honestly, kill yourself.
The statement "I believe there is(are) no god(s)" is clearly not an assertion of non-belief, but of belief. It is a negative proposition belief. A negative proposition belief is not the same as a lack of belief.
You are incorrect about the opposite of A. Again, there is no opposite because it is not a belief that can be inverted, it is the absence of belief altogether. You could try to argue that the opposite of absence of belief is existence of belief, but given that we're discussing the absence of belief with regards to god(s) the existence of belief regarding god(s) could go either positive or negative (belief that god(s) exist, belief that god(s) do not exist), so your conclusion still does not follow.