Again, you are bundling together the concepts of belief and knowledge. Knowledge is a subset of belief. Both are defined by different words: (a)theism is about

Again, you are bundling together the concepts of belief and knowledge. Knowledge is a subset of belief. Both are defined by different words: (a)theism is about belief, (a)gnosticism is about knowledge. The first dictionary hit I get on atheism matches my claim: "disbelief or lack of belief in the existence of God or gods."