To me, it's more-or-less accurate to call atheism a worldview.
"This world has no gods in it." is a statement about the world, even though it is a negative statement. I guess people are correct to point out that atheism is a lack of belief and, hence, a "lack" of a worldview. But that's splitting hairs. We know what folks mean when they say "worldview." Probably best to just proceed from there with the conversation at hand.
Atheism, on its own, is not a comprehensive worldview in the same way that theism isn't. Atheism is simply the absence of belief in gods or deities. However, to arrive at this position, individuals adopt or develop broader worldviews that inform their stance on the existence of deities. These worldviews can be philosophical, scientific, or based on other belief systems.
Similarly, theism, which is the belief in gods or deities, is not a worldview either. Theists often incorporate their belief in gods into a broader worldview that includes moral values, metaphysical beliefs, and interpretations of the world.
In both cases, whether atheism or theism, the specific worldview adopted or developed by an individual will vary, and it's this broader worldview that provides the framework for understanding and interpreting the world, including beliefs about gods or the lack thereof.
In other words, when someone says they're an atheist or theist, it would then make sense to ask them, "Ok, so what's your worldview that causes you to hold that stance?"
Edit: Though if I'm understanding your comment correctly, you may have already meant everything I just said, but you were fairly vague, so it was difficult for me to know that for certain.