Being an atheist doesn’t imply belief in the Big Bang, evolutionism or any way of life.

One could be an atheist convinced that dinosaurs are a fabrication, nothing more than funny looking rocks some weird junkie decided to give some absurd meaning to, that the universe has always been the way it is, that the Romans never existed, and that we should all live in the mountains, only eating whatever we find in some specific dark caves filled with the appropriately colored glowing mushrooms.

All for no other reason than that it makes them feel good.