I wish I could upvote you more. "X is a religion" should only be valid when X categorically resembles a religion--books, worship, in-group perks, rituals, supernatural, the lot. Your sports team analogy is great.
The new testament: http://www.amazon.com/Inside-Macintosh-Apple-Computer-Inc/dp...
The book of common prayer: http://www.amazon.com/Macintosh-Human-Interface-Guidelines-C...
The dead sea scrolls: http://www.amazon.com/Apple-Reference-Manual-Computers-030-0...
The Apocrypha: http://www.amazon.com/Newton-2-0-User-Interface-Guidelines/d...
Deuterocanonical: http://www.amazon.com/OpenDoc-Programmers-Guide-Apple-Comput...
Dianetics: http://developer.android.com/guide/practices/ui_guidelines/i...
Books, worship, in-group perks, rituals, supernatural; are just side-effects and the scale of it depends on the ability of its leaders to bullshit people.
I'm not an atheist btw - that also requires belief and too much energy. As I'm too lazy to answer the question "does God exist or not?" guess that makes me an agnostic - and truly I don't give a shit.
But then again, I'm an Ubuntu user that also uses Windows from time to time. And Ubuntu Christian Edition is a few clicks away if I ever make a decision :p
Do you admit the possibility that tomorrow, based on weird but explainable phenomenons, molecules in the air might collide and materialize a tuna-sandwitch right before your eyes? Think about it - possibility is so close to zero that intuition would tell you that it is impossible.
And yet atheists are ready to admin that this wonderful and full of life world that we live in (which is a lot more complex than a tuna-sandwich btw) - came into being by way of some kind of cosmic accident that we'll never understand, with our universe instantly expanding, forming lots of hydrogen-burning stars and rocks of all shapes and sizes - and somehow on one of these rocks, carbon-based life not only happened, but it also gave birth to sentience.
This story is even more unlikely to happen than a tuna-sandwich integrating right before your eyes tomorrow, or having a man in red suit driving a sleigh with flying reindeers and yet we consider it natural because it already happened.
That's why I said atheism also requires faith.
Can you point to some atheists who are as you say? As an atheist I've never considered this a particularly wonderful and full of life world (sure I like it and want to preserve parts of it but there's a lot of improvement to be made) nor have I considered the mysteries of the universe are incomprehensible. We are as Sagan said "the universe trying to understand itself".
You may say our lives coming into being by the known fundamental laws of physics is as unlikely as Santa existing, but here we are, the evidence is actually in front of us, humans and quantum mechanics. I've never seen Santa, yet I've seen humans and studied some QM.
Edit: oh hey, I almost forgot. http://lesswrong.com/lw/i8/religions_claim_to_be_nondisprova... "The earliest account I know of a scientific experiment is, ironically, the story of Elijah and the priests of Baal."
You're also an agnostic if you can honestly make the claim: "It is unknowable whether or not there is/are god/s".
I used to call myself an agnostic because, for whatever reason, people always assume that if you are an atheist you hold the position that there are no gods (which you also seem to hold given your assumption that atheism is a position that requires belief).
worship: http://www.google.de/images?q=steve+jobs+messiah
rituals: the constant plugging in of iphones and ipods into iDevices to recharge/setup
Couldn't resist ;)