Acts of worship you say? No, sorry, not a requirement to be a religion, nice try though. Religions are manmade constructs meant to control people using a belief system, and that is what atheism is.
But atheism is not a belief system.
It is the opposite in every respect.
Many theists seem to try to pull atheism down to the same level as theism, but this can only fail and turn against them as it is so obviously absurd.
I personally do not believe in a god (anymore, I was a christian once).
So my atheism can not be a belief system.
It is not a system either. I just don't believe in invisible magical big brothers in the sky, in heaven or in fairyland.
It is not a construct either. Non-believe is so simple that it needs no construction like god-belief does.
There is nothing to construct. It is just a simple lack of belief in magical and supernatural nonsense, in this particular case magical god beings.
And that is all there is to it.
I am not part of an atheistic religion that tries to control my life.
I do not believe in kobolds either and there are no a-koboldists who try to control me either.
I am an individual that belongs to no organization.
I do not believe in what I consider to be unrealistic, irrational magical stuff including magical gods and kobolds.
As to atheism not being a religion, funny, but it sure looks like one to me. A belief based on the precept that deities don't exist, based on no evidence at all, which oddly seems to fit every OTHER religion out there.
You are using a very particular definition of atheism that only theists seem to use as a twisted instrument in discussions.
You are free to do so, but I do not recognize myself in it.
I call myself an atheist, because I am without a god ( a = without, theo(s) = god).
I am without a god because I know not a single valid reason to believe in one (if you do please pm me).
I am not the one that has to prove there is none.
You can not prove that something that is not there... is not there, if it's description is so vague and purposely evasive as to try to escape any form of scrutiny.
I do not need to provide evidence that this vague magical being does not exist, like I do not need to provide evidence that kobolds and fairies do not exist.
Those who state that this magical thing exists should provide good evidence that it does (but only if they wish to convince others).
That is what is rational and what makes sense from a philosophical and from a practical standpoint.
I am not against the existence of a god in general and can be persuaded by evidence, although I am disgusted by the god of the books (bible, koran, tanakh). I think those particular gods are immoral, evil monsters and it is a good thing that these depraved constructs are just figments of the mind.