I thought that NS's example of not being a Marxist is very good.
I like the word 'lack'. If you lack a belief in God, that cannot be considered a 'world-view'. For example, an atheist need not be a materialist. I believe that there are some who are dualists, and it is conceivable that an atheist could believe in the soul or the afterlife.
It's interesting that there seem to be a very large number of things, which I lack a belief in, you might even say, an infinite number. However, you would not say that each lack represented a world-view! I lack a belief in Zeus, for example.
What is interesting is why some theists want to argue that atheism is a world-view. I'm not sure really, I suppose they are setting up a straw man, to knock down, but it doesn't work, but of course, they keep trying!