Each to their own, but...
Aethism is a belief system. in that respect It is no different than a religion. It's adherents claim that those who are not aethiests believe in sone sort of sky fairy.
Some aethiests believe those who are not aethiests are heretics, whereas some believe each to their own so long as they don't impose their belief on others or injure others in the process of following their belief.
Do try and prove me wrong if you want - but maybe that should be in a different thread.
Like you say - not sure it's the thread for such a substantial topic, so I'll simply state my position. Atheism is basically a default stance, there's no consistency or common belief requirements for atheists. And it doesn't make any statement on religion at all. It is simply - as the name suggests - categorising you as "not a theist" i.e. not somebody who says they believe in god. That's it, there's no other pre-conditions. You don't need to think any of the things you've stated above to be an atheist.
Many atheistic people are members of religions - like some Buddhists or new age spiritualists - so in this instance you're suggesting those people would have multiple religions, which doesn't make much sense to me. You can have agnostic atheists, who are the woolly "I'm not sure" people. You can have anti-theists (which are the type of people you are describing above). None of these people believe in a god, so they are not theists, ergo they are atheists - you are either one or the other. If atheism is a religion then it suggests that the definition of religion being used here is very loose to the point of being useless, as it is describing an incredibly broad group of people who may have completely conflicting belief systems, lifestyle, culture etc. and zero common cause.
I’d guess that the vast majority these days are agnostic.
That's kind of my point, I would estimate the vast majority of atheists are agnostic. They just don't care, or haven't thought about it, or they have but decided they haven't got a strong opinion on it. I consider myself as both an agnostic and atheist. In a colloquial sense, that would make me what people call just "agnostic". But really these are two different statements. There's this strange ardency out there of people thinking atheists are making a positive assertion that there is no god (gnostic atheism). That's not necessarily true, they just don't believe in a god. These are two different things, and part of the problem is people talking across each other using different definitions.
The whole thing is founded on the fact you can't prove a negative. So you can never prove god doesn't exist. You can only say that based on the evidence we have, you haven't seen proof that he exists. Which is by definition agnostic atheist.