It is correct that atheism is not a belief system in itself, but it will inevitably be bound into a belief system
The problem here is an equivocation of the word 'belief'.
In common parlance we would use 'belief system' to point towards religious belief.
So we might agree that atheism is a position on a single issue, but I would still not say atheism itself is bound up in a belief system of any kind, there may be some commonly associated ideas, but these are not necessary for atheism, and certainly not themselves a belief system in an meaning of the term other than simply a set of ideas.
To call atheism a belief system is to call being Lib Dem a belief system or a fan of ice hockey a belief system, it renders the word meaningless as it is universally applicable.
The problem here is an equivocation of the word 'belief'.
In common parlance we would use 'belief system' to point towards religious belief.
So we might agree that atheism is a position on a single issue, but I would still not say atheism itself is bound up in a belief system of any kind, there may be some commonly associated ideas, but these are not necessary for atheism, and certainly not themselves a belief system in an meaning of the term other than simply a set of ideas.
To call atheism a belief system is to call being Lib Dem a belief system or a fan of ice hockey a belief system, it renders the word meaningless as it is universally applicable.