I'm trying to make it make sense to me.
Certainly.
Because there are sooo many unique compilations of beliefs regarding all aspects of life, it does not make sense to me to pick one (like atheism) and call it your worldview; why not just call them your opinions?
Perhaps then, it is simply a matter of simplicity of speech, or an understanding that some issues can fundamentally affect other areas of belief such that focusing in on that aspect can cover a lot of ground in terms of how the concept of worldview relates to a broader conversation.
So, while it is understood that a theistic (a very broad general category) is one aspect of a particular persons complete worldview, whatever is being discussed is most impacted by that worldview contributing belief system. One may say "your theistic worldview" while fully realizing that what is meant is "your worldview which contains this or that particular theistic belief system".
If you want to substitute 'belief' with 'opinion', fine. If you would rather not use this term 'worldview' and instead use something like "your complete set of opinions on all aspects of life", that is fine too. I think most folks have an idea that it is simply a shorthand way of saying "all the stuff you believe about the world" with any adjective attached acting as a que that the speaker is focusing on a particular subcategory of what makes up one's worldview.
In my view, anyway.