You are absolutely right. Atheism is a belief.
Just like the belief that gravity exists. That the sun will rise tomorrow. That there are no invisible fairies living up my rectum. That F=ma.That there is an exterior reality etc.
Basically we cannot be sure of any knowledge, so an statement on ontology must be based on belief.
Now do you have a point with the trivial fact?
I dont believe in Krishna, invisible pink unicorns, gnomes, big pink bapy gods circling mars, and since yu now have been introduced to all these concepts you now are a believer in the non existanse of all these thngs, I just use the same metering stick on the many christian gods, and believe in none of them, you choose otherwise.