Most atheists are agnostic atheists that do not accept the proposition that a god or gods exist. They make no claims.

Theist: There is a god. (claim)

Atheist : I'm not convinced. (Rejection of the claim)

Because society is so heavily influenced by god belief, there exists a term for those that reject the god claim. Most do not believe bigfoot exists, but there's no special "abigfootist" word for the same exact position about not believing in a god. And people don't go yelling at "abigfootists" to prove bigfoot does not exist.

There are some atheists that claim there is no god, and that would absolutely require evidence.