No
An atheist believes that no supreme beings exist
It's a lack of belief, not a belief in a lack
It's a subtle difference in wording but a major difference in meaning. The difference is that the latter in an assertion. Atheism does not assert anything, it simply rejects the assertions of other religions.
kind of like how evolution is a belief
evolution is not a "belief"
it's a scientific loving fact
This.
Also if you're attempting to say that all atheists accept evolution and therefore form a common set of beliefs, no they do not all accept it
On top of that, Atheism isn't a lack of religion. It's a lack of belief in divine beings.
Technically true, however in the context of the prevalence of theistic religions in western society, lack of religion is heavily implied.
more like a theory
I really hope you're not attempting to abuse the word 'theory' in an intellectually dishonest way the way creationists do with their "it's only a theory!" thing
A scientific theory is backed with a lot of supporting evidence