There is a simpler refutation of Atheism and Theism alike. Both presuppose that you can define that ("God") which you are either affirming or refuting. But you can't. If "God" has any meaning at all, it is a personification of the Sacred, and the Sacred, by definition, cannot be defined (in the literal sense of being differentiated from that which it is not) since it is, by definition, all-embracing. And personifying the Sacred, by calling it "God" or "Allah" or anything else, is every bit as useful (and limited) a way of conceptualizing it as any other (i.e. "the Dharma" which is NOT personified, but still alludes to the Sacred.)

For indigenous tribal cultures, the Sacred inheres in nature spirits and ancestors;

For Hindus, Buddhists, and Taoists, it inheres in the "inescapable network of mutuality", whether called the Tao or the Dharma;

For Western Abrahamic traditions, it is personified as "God" (or Allah, or JHVH, or whatever)

And for "Secular Humanists" it is called "reason".