“Do as you will” is the creed of any religion which no prohibitions on behavior. If a religion has any prohibitions on behavior, then it’s creed is not “Do as you will”, which is why neither Satanism nor any individual person’s religion could possibly be a “Do as you will” religion.
I don’t argue that atheism’s OPERATIVE creed is “Do as you will”, but rather that it’s PROFESSED creed is “Do as you will”, which is simply a lie.
An atheist’s religion is never “Do as you will”, any more than a satanist’s is. BUT, both satanists and atheists PROFESS that their is no authoritative rule which commands them to “Do anything OTHER THAN as they will”.
They say they are allowed to “do as they will”, if they wish, and no one can tell them anything differently, but they do not in practice “do as they will” because their religion has behavioral prohibitions.
Atheism qua atheism has the goal of removing the idea of “deity” from anything which it’s adherents come into contact with.
The removal of “deity” from one’s set of beliefs has the natural consequence of trying to “convert” anyone who displays any belief in “deity” from their “foolish belief” to the obvious sensibility of being “deity free”, like themselves.
Once you know what the real meaning of religion is, which is simply the operative set of beliefs of a person by which they act in the world, then you realize that all people possess a (their) religion and that the natural human (charitable) response to being presented by beliefs different from yours is to help them undrstand why yours are better (why hold beliefs you don’t consider better?), and that EVERYONE is in the process of “converting” others to their religion at all times.
That is the GOAL of every person’s BEING a person, ie helping them become better people, which is not somehow “magically removed” from the so-called atheist by his calling himself an atheist.
Christianity’s GOAL is to help more people become Christian.
<Your religion’s name here>'s GOAL is to …, likewise.
Why would atheism be excluded from this characteristic of all religions?
I’m sure you were, but the real answer to your question is that any religious community gathers wherever it wants. That some of these groups don’t have a need to possess buildings is irrelevant to it’s “gatherings”.