Greetings, Belle Rose!
To answer your question, it only takes two Natural gametes, male and female, to create an Atheist, since everyone is born lacking a belief in a God or Gods.
No supernatural being is required, nor does one exist, M’Lady. *Tips fedora.*
(I finally broke down and bought a fedora to make official my Smug Atheism. A Nice black pleather one. I deliberately bought it small to make my head seem bigger. Back in my college days in the late Eighties, I had a fedora and I was an Atheist, but I never associated the two and the Internet wasn’t ubiquitous enough to widely spread the Smug Atheist in a Fedora meme. Did I help create that???)