…atheism is not a religion, a philosophy, or a worldview. It is not the conviction that there are no gods. It is nothing more than the lack of theistic belief. Of course, most atheists believe all sorts of things. What they have in common is that they do not accept the theistic claim (i.e., that some sort of god or gods exist).
You already know what it is like not to believe in some gods. There are plenty of gods that have been worshiped by humans over the centuries, and you do not believe in most of them.
The atheist is just like you in this regard; he or she simply goes one more step and does not believe in your particular god either.