All animal brains (including us) are first and foremost is a great signal processor that is tuned to surface that particular reality of nature to us that helps life.
Life is the evolution of (increasingly) complex adaptive systems in non-equilibrium state, driven by external energy and enabling a new regime of faster entropy increase, thus faster descent towards the "heat death". This is contrary to the popular belief that life somehow goes against the 2nd law of thermodynamics. In fact, it is the 2nd law of thermodynamics, the universal drive towards higher-entropy states (we are essentially specs of dust in a slow-motion explosion, since the Big Bang), that enables life-like systems to evolve under the right conditions to accelerate the slide towards a higher-entropy state.
Specifically in case of carbon-based biological life, one succinct tongue-in-cheek way to put it is "life's purpose is to hydrogenate carbon dioxide". See the "Nick Lane" discussion thread from today: https://news.ycombinator.com/item?id=32392937
This is your opinion. There are other possibilities.
They are unprovable but irrefutable delusions or part of frameworks people made up to come to peace with the truth.
Examples frameworks would be pitiful reasons to exist like "keep the species alive", "keep the family line going", "I need to be behave this and that way because my deity will judge me when I die" etc.
Regardless, this (particularly, the conceptualization of the supernatural) is somewhat of a variation of the kind of thinking that I'm referring to. I don't disagree that this isn't formally documented in scripture, but nonetheless it seems to have somehow ended up broadly installed in minds (both theist and atheist, to be fair), not unlike how various behaviors can be observed in theists despite it not being a part of formal scripture.
In reality atheists don't have anything in common with one another. There is no shared belief system or a set of scriptures for atheists. Stalin and Mao did however have a shared belief system and it wasn't atheism.
This seems unlikely.
> There is no shared belief system or a set of scriptures for atheists.
Large quantities of those I talk to on the internet seem to disagree.