"Atheists believe god doesn't exist"

Actually, no they don't. Atheists don't believe that a god does exist, just like most reasonable adults (theist or otherwise) don't believe leprechauns or unicorns exist. Atheism really is very non-controversial, is the default setting of the human mind before it is enculturated, and is plausibly supported by the entire catalogue of reliable human knowledge that has been accumulated over the 4 million years of our evolution.

Theists are the ones out on a limb epistemically. They each need to justify why their own particular imaginary friend is different from every other imaginary being humans have ever made up. Of course, just like the tool in the video, this is their best effort: