No, it isn't. And yet while the rejection of a claim is not a belief, the rejection itself must be made on the premises of a separate and contrary belief system.
For example: You reject Christianity, that is not a belief. The fact that you reject Christianity however immediately shows that you have some other ideas you have taken as true that Christianity goes against. If not, you would have no reason and basis to reject it.
I pulled the above quote out of your last post. Star Stuff, for whom your words were intended, has already responded, but I'd like to add a little more.
My atheism does not need any alternative to gods. I am an atheist because the idea of any sort of god seems so unlikely that the idea is not worth considering. I don't replace the concept of religion with anything else. I simply don't include it in my repertoire of thoughts and ideas. Those thoughts and ideas, which seem to adequately provide me with a workable explanation as to why we are here and how we function and why bad things happen, are not an alternative to religion. They are religionless.
In the above quote, you said "If not, you would have no reason and basis to reject it". You seem to assume that religion itself has enough innate legitimacy to require purposeful repudiation. In my view, it doesn't. It is merely a philosophical stance held to be true by some for no obvious reason. I don't have to allow for it and compensate simply because I rejected the notion. No void is left behind that requires filling, no darkness is left behind that demands new a new light source.
It is simply like loosing an extra hair out of my balding head. I don't have to wear an extra hat to compensate for it. The loss is too trivial.
I didn't reject religion. I shrugged it off. And there was no need to replace it with anything when it was gone.