The word atheist is really not needed though. It’s just a word in popular usage by mostly religious folks who think someone ought to believe in some sort of invisible higher power so as to secure their soul from eternal damnation.
But, the foundation of such is flawed. Such insinuations about a “soul” and “afterlife” comes from the realisation of the futility of life. A lot of people don’t want to come to terms with certain depressing aspect of life – that everything eventually comes to naught.
However, it seems though the so called atheists have made peace with reality and do not intend to cloak it by subscribing to unproved comfort zones that exists in made up religious texts. This is why for most, the concept of afterlife in a cozy heaven singing kumbaya does not strike a cord regardless of the God offering the wonderland.
There are more than four (4) thousand Gods with different worshippers and people that adore them. Why don’t you believe in all, why stop at one? You could literally go to the hell kept by the other Gods you don’t believe in, right? But, to each their idiosyncrasies.
The truth real truth about heaven is that most adherents of the popular faiths get lost in the euphoria of the mass adulation and start misplacing built up practices from different cultures to exalt their belief system. But, for every known God that you do not believe in, you are an atheist to it.