It may remind you of religious zealotry, but that doesn't make it a "religion."
I agree with that, and I said exactly as much.
To answer your question, I'd say that considering atheism to be a religion is rather like considering Christianity to be a religion, in a sense. In a very specific sense. Christianity, of course, is a broad umbrella term which includes many religions. More, I'd argue, than even the OP included in his poll. But, hey, you have to draw the line somewhere. The term atheism works sort of that way as well.
Of course one classification system for religions--but probably not the only one--is to group them by the number of deities supported. Thus, a religion might be called mono-, poly-, or atheistic. So in that sense atheism, while not specifically a term referring to a single religion, might be a characteristic of a large number of religions, mostly extinct I'd imagine.
Atheism, of course, can also refer to the non-religious variety, and, increasingly, to the anti-religious variety. Anyway, Hockeydude's schtick has always been more anti-religious rather than irreligious. It's fine, of course. I just think we should call it like it is.
As for your definition of religion, it's not bad. It used to be the three Cs (and Hockeydude's brand of anti-religion certainly has all of those), but now it also includes something about Ultimate Reality, or what you call "metaphysical truth." This, of course, is lacking in Hockeydude's on-line persona, although whether it exists in his real persona I can only speculate. This is precisely why I used the subjunctive, and I would not argue with the statement you made that I quoted.
Certainly I have nothing against the irreligious, and consider myself among them, but the anti-religous are another matter altogether. They can be as zealous as the most zealous inquisitor, and might go to similar lengths to install their own philosophy if circumstances allowed. Hockeydude is young, though, so I don't think his bigotry will last forever. I think that in time he'll develop a don't-give-a-sh
it attitude toward religion, like most people have done.
I'm pretty shallow myself. Unspiritual may be a better word. I voted Roman Catholocism, since I was baptized in the name of the Father and of the Son and of the Holy Ghost, and I was communized (if I can coin the term) in youth and confirmed in adolescence. My mother also taught us to say Grace, although you could probably count the number of times we actually said Grace on the fingers of one hand. Mostly, she didn't want us to look like bumpkins when certain relatives visited, although among ourselves my nuclear family didn't stand on ceremony much. Once in a great while we'd go to mass, but that was probably less than once per year. For me, the religious experience was always more academic rather than spiritual. In the same way that I liked Algebra and Spanish and Literature in school, I liked learning the stations of the cross and their significance in catechism. So Catholicism becomes more of an ethno-religious identity rather than a religion, per se. (some of the Cs are missing, I suspect) I suppose I haven't been to mass since about 21 years ago, and that was a requiem mass. It was probably at least ten years before that I attended a mass. That really wasn't something we did regularly as I recall. Still, as I am, in such polls it seems natural and pro-forma to check off Catholic. I assume that's the way it is with many posters.