I have yet to see a definition of worldview which was not a set of beliefs, propositions or the sum total of how a person sees the world. Could you provide one?
http://www.oxforddictionaries.com/us/definition/american_english/worldview
http://www.merriam-webster.com/dictionary/worldview
This is really a simple matter and I am surprised at the vehemence with which it is met.
Atheism of every sort entails some belief about the world. That one can distinguish atheism from theism implies that it is a worldview.
I have already listed some of the beliefs that are true of atheists, excepting implicit atheists.
If you are an atheist, all you need to ask yourself is does your atheism inform how you think of the world? Does it entail anything?
If so, then it is a worldview. Though a few might try to argue that it is not comprehensive enough to establish a "worldview" I disagree. To hold such means that the concept of worldview can only apply to individuals. For no set of beliefs are identical. Clearly, this world is used to describe categories. How can this be so, in such a way that excludes atheists? It does not matter that atheists may diverge in various categories, if some set of beliefs are entailed from their lack of belief then atheism is a worldview. This works with every category of atheist, excepting implicit atheists not able to form belief....so babies, rocks, people with brain damage. Moreover, negations can entail to form a view. And since we can describe our view by what it is not, this too adds to the merit of the term atheists worldview.
We are describing similarities in how a category of people view life. When we label that category atheists, there are similarities. And as such, we can appropriately group those similarities.
One need be careful in doing such, so that the actual beliefs are entailed by membership to the group, so saying that part of the worldview is empiricism, or materialism is erroneous, but saying there is such a thing as an atheist worldview is not.