What principle of atheism denies the existence of a god or ultimate reality?

The principle that denies the existence of a god or ultimate reality aligns closely with the idea that everything evolves through natural processes. Atheism typically holds that the universe and life can be explained through scientific theories, particularly evolution, without resorting to supernatural explanations or deities. This viewpoint emphasizes a naturalistic understanding of the world, focusing on observable phenomena and evidence rather than faith or divinity.

In contrast, the other options present ideas that are not fundamentally linked to atheism itself. The belief that humanity is inherently moral does not inherently deny a god, as moral frameworks can exist within both theistic and atheistic views. The assertion that religions provide necessary guidance implies an acceptance of religious structures, which atheism typically challenges. Lastly, the view that spirituality is essential for balance suggests a reliance on non-material aspects of life, which atheism generally disputes by prioritizing rational, scientific explanations over spiritual beliefs. Therefore, the correct answer reflects the materialist understanding of evolution that is central to atheistic thought.