With some notable exceptions like political and atheist author
G.H Smith, it is. Philosophers such as
Ernest Nagel dispute the definitions being forwarded by such authors as not being 'true' atheism.
Much is dependant on the individual and how they wish to label themselves...Gilly is entirely correct to describe himself as Agnostic and not Atheist. If someone wants to label themselves differently then they are well within their rights to do so also, however labelling others is the issue and it largely depends on the position of the person applying the label.
I am not an atheist because I do not deny or have any position on the existence or non-existence of God, essentially that makes me Agnostic although I also think the question 'does God exist' assumes things we do not yet know, so effectively I am Ignostic.
(Note in Hatters posted definition of Atheism it states a rejection, which is a cognitive definitive...which belies his opinion and in fact supports Gilly)
You don't have to hold a position to reject another persons assertion as being flawed.
It's a pointless debate as it's simply quibbling semantics, but the bigger problem is when theists feel the need to imply that an absence of faith is also a form of faith (which is a flawed concept) - not saying you are doing this, but it's something people who lack a belief in a deity have to contend with.
The only reason the point is brought up constantly is due to people trying to force a personal & subjective definition onto others.
I hold no views about a god/gods - I don't accept the assertion that "A god exists" due to lack of evidence.
I don't hold a view about it's existence either way - no data exists to make a judgement.
(the above is my atheism)
I also don't believe it's knowable either because what's been proposed by most theists is an entity which exists outside of our known world & therefore not testable in the same way as other theories.
(the above is my agnosticism)
As a result of my default lack of belief in gods, combined with the nature of what's been proposed - I'm an agnostic weak-atheist.
I reject the assertion without making a counter-assertion of my own.
Hatters is only wrong if you reject his definition as flawed, which I'd be pressed to find out exactly where his logic is wrong - simply saying that others label it different doesn't undermine his argument.
All sub-categories need to be taken in account if you want to take into account every scenario, implicit, explicit, weak & strong.
Implicit Atheism - always weak. / does not believe due to no exposure to the concept (baby's, isolated communities etc)
Explicit Atheism - weak (does not believe, but does not state a god does not exist either)
Explicit Atheism - strong. (does not believe & does state that a god does not exist - or holds a belief that a god does not exist)
Almost every single rational person I've spoken to fits into the Explicit Atheism - weak (for atheism) & is also agnostic (as agnostic concerns knowledge not belief).
It's not really that complicated but it amazes me how much people debate these very simple points.
Note : While I agree all terms are stupid for atheism (as creating sub-groups for the rejection of an idea is stupid to begin with) these groups are only created in direct response to logically flawed assertions by the theistic community that rejecting a belief is the same as holding one - which is why you get the absurd level of trying to put babies into either group.
In reality you are believe in a god, or you don't.
One is a position which can have a whole culture & moral code/tradition - the other has no common attributes, belief requires a mind & a certain level of cognitive function - as does a rejection of belief , but no level of cognitive function is required to hold neither.