The End of Atheism

My last two posts have been dealing with a response that I got from an atheist (who I am calling Alec), and within them I revealed the inherent weakness of atheistic reasoning. I have unfortunately, one last flaw to reveal in his logic, and because it is not the biggest flaw he had, this will seem more like a parting shot than anything else. However, I cannot let such a glaring error pass by me unchallenged and unexposed.
Alec began his response thusly: "Atheists are not obligated to follow your or anyone else's idea of what atheism is. Not Nietzsche's, not Wells', nobody's." Now, what is he actually saying? What he is actually saying is this: there is no fixed definition of atheism. No one is the authority on atheism (not even atheists themselves: "Not Nietzsche's, not Wells', nobody's") and thus all definitions are mere subjective opinions that carry no real weight in regards to atheism's actual definition. Thus, just because Nietzsche or Wells (or myself) say atheism is such-and-such, Alec is under no obligation to believe us because there is no authoritative statement on atheism, only opinions on atheism that can be believed or discarded at will and/or preference. What's atheism to you may not be atheism to me, and what's atheism to me may not be atheism to you.
Alec shoots himself in the foot, however, within the very next sentence: "Atheism is defined thusly: The absence of a belief in a god. Period. End of definition." Okay, first he tells me that there is no fixed, authoritative definition of atheism, then he goes and defines atheism in an attempt to convince me that that is what true atheism is. If there is no fixed, authoritative definition of atheism, then by what grounds am I obligated to believe that his definition is any more truer than Nietzsche's or Wells' (or my own, for that matter)? If there is no ultimate idea of what atheism is, if all is merely subjective opinion, then how do you even begin to have a standard by which you can measure what atheism is? You cannot; without a fixed definition, all attempts to completely define atheism are lost, including Alec's complete definition ("complete" by his addition of "Period. End of definition").
Contrary to what you may be thinking, I am not twisting his words; I am hearing what he is actually saying (whether he knew it or not). Because he equally dismissed Nietzsche and Wells as well as me, apparently even atheist's definitions are not immune from the whole "[we] are not obligated to follow your or anyone else's idea of what atheism is." And because Alec is himself an atheist, that means that his own definition is not immune either. Therefore, it is equally as subjective and dismissible as Nietzsche's, Wells', or my own. In an attempt to remove any grounds for me to define atheism, he has removed any grounds for himself to define atheism.
"We are the (currently living) atheists and we will decide what the word means." If the word does not have a fixed, authoritative definition, and if no one (not even atheists) can give one, then how in the world am I to believe that any definition you all come up with is the true definition? What is there to prevent future atheists from saying, "We are not obligated to follow your or anyone else's idea of what atheism is. Not Dawkins', not Alec's, nobody's"? There is nothing to prevent it. In addition, if atheism has no fixed, authoritative definition, then chronological location ("currently living") is irrelevant; if the very idea of atheism cannot be authoritatively defined by anyone, then that includes "currently living" atheists as well as dead ones.
The further problem with atheism lacking a fixed, authoritative definition is even more devastating for Alec. If no one can define atheism (not even atheists), then we cannot know what it actually is; and if we cannot know what it actually is, then the very idea of "atheism" has no meaning. Therefore, we cannot know whether or not atheism exist at all. Ideas must have meaning (a fixed, authoritative substance) to them in order to exist. If someone says, "I don't believe in God," we can call that belief whatever we want to, but we cannot call it atheism, because (according to Alec's own logic) atheism is indefinable, and thus even the statement "I don't believe in God" cannot be called "atheism" because no one knows what the heck atheism even is! In this scenario, where atheism is indefinable, atheism as an idea ceases to exist. Making atheism indefinable is the end of atheism.
I do not believe that Alec meant to say all that, nor do I believe that all atheists are as dumb as my entries may make them sound like. What I do believe is exactly what I said in my previous post: when placed in the fires of logic and reason, atheists (though perhaps well-meaning and sincere) simply have not or do not think out their own ideas to their logical conclusions. Every time I read one of their blog posts, every time I read one of their essays or articles, every time, I remember what a friend of mine once said, "In order to be an atheist, you must be willing to live with certain logical inconsistencies."