Theism, Agnosticism & Atheism | Definition & Differences

Atheists will tell us that their atheism is not a belief or a worldview but merely a position on one topic, and that topic is God. Namely, they disbelieve in God because of a lack of evidence, and that's the end of it. But what does this lack of belief in God entail? Well, it entails a not-God model of reality—a model of reality that is purely natural. But what is the evidence that reality is purely natural? What evidence demonstrates that the grounding of existence is godless and impersonal? Th