Arguments against existence of God.

[T0 Th3 M4X]

Bingo! It's not a determining factor.  They could all be chickens, and it wouldn't hold any relevance because the study of cosmology isn't bound by their religion (or being a farm animal), and neither are their findings.  Atheism is an opinion and a religion, nothing more.

How can, not being convinced of unsupported theistic assertions, be a religion?

I can believe its constructs for whatever reason I choose and call myself an "atheist" or not believe them at all, and still be considered an "atheist." At the end of the day, it's just an opinion about "god(s) vs no god."

No, it's an opinion concerning the case FOR the existence of gods made by theists, not meeting its burden of proof.

Atheism is not necessarily the claim (or even the opinion) that gods do not exist. It is the position of not being convinced that gods exist. SOME atheists may go a step further and claim that no gods exist, but that is not requirement to hold the atheist position.

Views on assertions by theists isn't a requirement to be an atheist.  If no theists existed on the planet earth, you could still be an atheist.  If you never heard of any God or gods as a possibility, you could still be an atheist. There is no prerequisite that requires any form of evidence for anything that is a prerequisite to adhering to atheism.  There is no requirement besides a person saying that's what they choose to believe.  They can believe it based on what they believe to be evidence, or simply choose to believe it due to apathy. No matter how, it's still atheism.

Of course now many atheists have their own church, their own set of rules and guidelines, and what not.  Gatherings, hymns, offerings, tax exemptions, and religious rights.  If it looks like a duck and quacks like a duck...

Go go gadget atheist mega church...