Atheist beliefs? Are you talking about beliefs like "I should floss every day", or "reason is a helpful tool to explore reality"? Surely not, since theists can hold the same beliefs. Calling beliefs like these "atheist" would be silly.
Agreed.
Surely "atheist beliefs" would be beliefs that define the holder of those beliefs as atheist.
Right.
If you disagree, it should be easy for you to list a few necessary and sufficient "atheist" beliefs.
Which I've already done about 1,000 times, to no effect whatsoever, because this "atheism is not a belief" thing is a dogmatic emotional religious kind of belief, not a belief that can be addressed with reason.
Atheists believe that human reason is in a position to analyze the possibility of a God's existence.
This is a passionately held belief, despite any evidence of such an ability.
This is a passionately held belief, despite the fact that Gods are generally defined as being outside of and above reality, and thus would logically be beyond the reach of the tools we have developed for understanding reality.
This is a passionately held belief, despite the reality that internet atheists are generally desperate to get on to a debunking of the god proposal, before they even understand what the proposal is.
This is a passionately held belief, which is fundamentally emotional in nature, just as theist beliefs are.
That is, as humans we are desperate to believe we understand and therefore can control our environment. One groups yells, "Religion has the answers!". Another group yells, "Science has the answers!" And then the two groups proceed to arguing over who is right.
When it comes to analyzing known and knowable reality, science has a great case to make. But this question may not be about knowable reality, as many theists have proposed for a very long time.
All that said, it doesn't matter the tiniest bit what I say, because you are not listening on the reason channel.
The profound contradictions clearly evident within both theism and atheism tend to illustrate that a greater intelligence of some kind may also be fully contradictory, and thus beyond the reach of reason.