There is a God:
If the legal world were to define religion by only the belief in a god. Some, such as Buddhism, Taoism and Shinto — even Scientology — would be free to be discriminated against. Due to not having legal protections.
[A.D.D. Moment] Why is someone I presume to be a Christian trying to say that Atheism is a religion when that only sets the stage to eviscerate their own?
There is a common belief:
Atheists are bound by no common ideology or belief. An atheist is someone who does not believe in god. Period (remember Atheism also includes Buddhists, Shinto's,etc). Beyond that, things get a little murky. There are the secular humanists, there are logical empiricists, there are existentialists, there are skeptics, nihilists the list goes on. Not all atheists believe in evolution or put their 'faith' in science. Atheists as a whole are bound by a common thread -disbelief- and nothing else.
[A.D.D. moment]If disbelief makes it a religion then everyone who thinks Obama isn't a legal citizen and thus is not allowed to be President also counts as a religion.
There are absolutely no laws:
All religions have a set of laws or regulations ranging from what you can eat to who you may or may not kill or covet. In atheism, this is entirely absent.
There is no Church or Ritual:
The idea of an organized church of atheism in which its rituals are practiced by gatherings of (un)believers is a non sequitur. (Seriously, I shouldn't even have to break it down this far.)
There is absolutely no unified concept of spirituality:
Unlike atheistic religions such as Buddhism, and Jain non-religious atheism has no spiritual credo. Some atheists may consider themselves 'spiritual' (against Buddhists), while a great many do not. Some may feel some sort of connection to nature or the universe while others may feel nothing of the sort.
I suggest you look up the "oceanic feeling" in Civilization and Its Discontents by Sigmund Freud.
There is no scripture:
Christianity has the Bible, Islam the Koran; Judaism has the Torah, Hinduism the Upanishads and the Bhagavad Gita. Sikhism has the Guru Granth Sahib, Adi Granth (along with Janamsakhis,Dasam Granth). Jains have the Kalpasutra, Agama, Tattvartha Sutra, Sanmatti Prakaran. I could go on but, that is a post in or itself. Atheism has no scripture or sacred text. Darwin's Origin of the Species, while held in high regard by many atheists, doesn't really count.
Atheism has no Clergy:
In addition to having no rituals, atheism has no ritualistic leaders. Unlike virtually every religion known to man, atheism has no anointed hierarchy to lead its 'adherents' closer to the truth. This is not to say that there aren't prominent atheists. There are. But, absent the sacred texts and rituals of religion — not to mention a proper congregation — they do not constitute a priesthood or clergy.
There is no tradition:
Don't even need to explain this one.
There is no founder:
Buddha, Muhammad, Jesus, Moses, L. Ron Hubbard - most major religions have a founding figure or prophet. Atheism has no such figure. You could try to argue that old timers like Galileo who rose to prominence are the founders but, you'd still be wrong. Atheism has no founders and that is all there is too it.
There Are No Holidays
Most religions have holy days (still, despite the all-out assault on Christmas). Atheism has no holidays, and no framework to decide when such holidays would be or what they might commemorate. Festivus doesn't count.
There Is No Concept of the Afterlife:
Most religions attempt to answer the question of what happens to us when we die. Where do we go to be warmed in the loving embrace of the lord? Where do they go to be horrifically tortured? There's heaven and hell, of course, and reincarnation, nirvana and moksha. Atheists have no concept of the afterlife, except that, most commonly, there isn't one
[A.D.D. Moment] Don't try to say that the common idea of no afterlife counter me own statement. Just because a idea is common amongst a set of people doesn't mean that it's the standard.
There Is No Creation Myth:
Hold on, don't get ahead of yourself. You were probably about to jump and say "How is the Big Bang any less of a myth than Genesis"? Keep in mind that not all atheists believe in the Big Bang theory, it's different because it's a scientific postulate that can be tested and the effects of which can be empirically demonstrated. If in the end this theory does not stand up to scientific scrutiny, it will be chucked on the trash heap.
So, atheism shares none of the characteristics common to all belief systems commonly known as religions. Even widely-despised and derided belief systems like Satanism, Wicca, paganism and Presbyterianism are religions by these standards. Atheism is not. Arguing that it is means that faith in god, ritual, community, tradition, spirituality and theology are irrelevant. Religion then becomes an incredibly paltry thing. It is not a source of solace and spiritual wonder; it is not a vehicle for bringing symmetry to the chaos of life and meaning to the void - it's just the act of taking a position on the existence of god. That's it.
Now for those who wouldn't want to trash their own religion in hopes of sticking it to those damn Atheists. They have another argument and that is "Atheism is Faith". This is due to the convoluted nature of the supernatural because the existence of god can be neither definitively proven nor disproved, atheism merely replaces faith in god with faith in science. This is a much subtler argument but, none the less still poisons the well for everybody.
There is a fundamental difference between Atheism and Faith that cuts to the core of what religion is. Faith involves the belief in a god but, not only that it goes much, much farther. Faith is the trust in god and the acceptance of paradox and contradiction. It reveals the "revealed" truth as all truth and from there embraces the unknown. Science is not anathema to faith; it simply operates on a different plane of thought.
A common error is that atheists merely put their faith in secular 'gods' and call them by another name. Richard Dawkins, Darwin and Carl Sagan. But whether an atheist is drawn to the ideas of these men or to Nietzsche or Frank Costanza, it is not proof of 'faith'. Lots of people are admired, from the aforementioned thinkers to Ronald Reagan and Milton Friedman. We sometimes even use religious language and talk about how they are 'idolized' figures. But there is a difference between agreeing with someone or admiring them and having religious faith in them.
Now you can stop with the defense of "The law says it therefore it is". The only reason they even gave it that definition is so narrow minded theists couldn't discriminate against Atheist for having a differing idea. Keep in mind "Atheism" also includes Buddhist, Jains, shinto, tao, crazy "the universe is made of cupcakes on the backs of panda's"s, etc. So these people have religious protections since they can be classified as Atheistic. Remember Atheism is the disbelief in a god so anybody who doesn't believe in a god regardless of other beliefs counts as a Atheist. You can keep trying to hammer on "Atheism is a religion" until your arm is a bloody nub but, repetition doesn't equal correct.