I don't agree with the assertion that "Both atheists and believers in deities hold that the unknown (and so far, still ultimately unknowable) is known, and knowable." There are many different definitions of atheism, but the broadest one I've found says "a disbelief in the existence of deity" and doesn't claim any knowledge whatsoever. Some atheists certainly lean towards the more agressive end of the range. Another definition from the same source is "the doctrine that there is no deity", which seems closer to the way you're using the term. And some atheists definitely enjoy proselytizing.

Of course it all depends on what the definition of "is" is. I consider myself an atheist by my first given definition, although by some definitions I would be considered an agnostic. Wikipedia has discussions on differences between weak, strong, explicit, and implicit atheism.

"But the way so many people can get into so many ferocious arguments over things which are unknown and unknowable never ceases to amaze me..."

This points in a direction worthy of study all by itself.

FULL DISCLOSURE: I'm a Catholic, and yes, I take my religion seriously. But I'm also a highly educated man with an extensive background in the hard sciences. I think about my beliefs quite as seriously as I think about my trade, my political opinions, or any secular subject. The reason will soon (I hope) become obvious.

The "unknown and unknowable" is at the extreme edge of subjects for human mentation. In his classic Zen and the Art of Motorcycle Maintenance, Robert M. Pirsig noted that the arguments most beset by passion and high emotion are those whose subject matter is most clouded by uncertainty -- in other words, those subjects where objective evidence is insufficient to settle the matter now or in the future. There appears to be a deep human need for metaphysical commitment, whence comes a powerful sense of threat whenever one's commitment is called into question.

The explanation for this phenomenon approaches tautology. Metaphysics is that branch of philosophy that deals with the givens of existence; all other reasoning and intellectual commitment is founded on one's choice of metaphysic. To have one's mental foundations cast into uncertainty is to feel a shadow creep across one's entire mental universe. It's the broadest imaginable threat to one's sense of oneself as a rational entity.

Like it or not, the great majority of us invest heavily in a metaphysic that includes God. "Worse," if I may use that word without being drummed out of the Theosophical Brigade, an unfortunate number of "thinkers" endorse religion for its utilitarian value. From these things it seems inevitable that nominally non-theocratic societies that invite conversation and contention over religious matters should find those exchanges to be quite passionate, often in an unfortunate way.

The counter-agent is humility. But humility is a characteristic that's not easily learned by the intellectually vain -- yet another statement at the edge of tautology -- or those who have been taught from an early age that those who don't share "our" beliefs are really too stupid to bother with. It's a neat little trap.

The there's the practical atheist, who knows he cannot prove the non-existence of a creator, but is confident that none of the religions on offer are anywhere near the truth of the matter.

This realization is despised, because such a person is free of much spurious authority.

"I hate writing about this stuff because -- pardon me while I speak plainly -- the people on both sides of this issue are assholes."

There's always a asshole for every side, but in ID vs. Evolution debate, there's a side for every asshole.

I don't particularly like teaching ID in schools, but more importantly I wish they'd teach kids about the scientific method and how to analyze and argue and choose what to believe. That will serve them in all facets of life, too many people are finishing school not knowing how to make informed decisions.

For instance, there are still adults walking around who believe in ghosts and visions, but haven't heard of lucid dreams and therefore haven't even been given the chance to consider alternate explanations. (Carl Sagan noted in the Demon Haunted World that most visions happened upon waking up, which is also when lucid dream hallucinations happen). These people are ripe to get preyed upon.

I don't even know what I am. I call myself an athiest yet I find myself praying quite a bit. Maybe I'm just crazy and talking to myself, but it's hard to shake that idea that there's someone out there when you've grown up with it.

Come on, Eric. You know better than to say something like that. Show me where an atheist proved there is no god.

What Joe R and Brett said goes for all athiests.

Let me first agree that fanatics of all stripes, including my co-religionists, resemble each other far more than they would admit. I am also not a a young-earth creationist and don't believe ID should be taught in public schools.

That said, I find that atheists demand a level of proof that they do not seek in any other area. For some reason, only an iron-compulsion deductive proof of deity counts as a "real" argument to them. Yet we use inductive reasoning orders of magnitude more often in everyday life. This is not just for aethetics, or philosophy, or social beliefs, but nearly all of our everyday acts: driving, shopping, understanding what is said to us, making up a budget.

There always seems to be an almost nasty glee taken in atheists' pointing to lack of mathematical proof, as if they had achieved some superior wisdom. It is often the glee that raises suspicions. Brett's comment that he is one of the chosen few who is free of spurious authority is the sort of hubris we all find comical when people use it in other realms of thought. It furrows the brow, causing me to think "hmm, sounds like a personal issue here."

All that we take in is ambiguous evidence of any number of possibilities, some contradictory. We draw conclusions for getting around in the world based on the aggregate - where does the evidence most likely point? This is not an artificial attempt on our part, it is what our brains actually do at a neurological level while we develop. We could not speak, or throw a spear, or recognise a face without these shortcuts of thought.

And these shortcuts are not arbitrary, nor do they fall apart when disected. Atheists may consciously reject any religion they can name or imagine, but then revert instantly to complete confidence about knowing how the world works. They have a religion, it is merely a subterranean river.

I find few claims more irritating to atheists, and that irritation, that outrage and contempt should give them pause.

Even in law we have different standards of proof: beyond a reasonable doubt, clear and convincing evidence, preponderance of evidence. Atheists - okay, some atheists; I have overgeneralised throughout here - insist on the standard for criminal conviction, while living in a world of civil dispute.

Some folks who call themselves atheists are merely those who are uninterested in the topic. I don't think any of us can gin up interest for long in subjects that bore us. But as a practical matter, if a god exists, the matter is of infinite importance; if none exists it is of no importance at all.

I hate many atheists. They pretty much seem to just belong to a different religion and a darn intolerant one at that.

I always say, 'I don't believe in a god.' because that's what I believe. Now, I can usually tell you why I don't believe in a particular god, but I don't know. That's why I always say, "I believe". If the Catholics are correct, I'm in big trouble but at least I'll be able to ask Him a few pointed questions before I go to Hell.

"All that we take in is ambiguous evidence of any number of possibilities, some contradictory. We draw conclusions for getting around in the world based on the aggregate - where does the evidence most likely point? This is not an artificial attempt on our part, it is what our brains actually do at a neurological level while we develop. We could not speak, or throw a spear, or recognise a face without these shortcuts of thought."

This strikes me as being very correct, but I don't think it's a trait exclusive to the topic of religion, and certainly no indictment specific to just atheists.

Maybe I've misunderstood you, but I get the gist that you think atheists are either going out of their way to come to a conclusion which all other senses say is false, or that they've reached that conclusion only because of disinterest in the subject?

Jared, thank you for your reasonable response. I am saying something close to both of those possibilities, but not quite either. I believe (many) atheists are going out of their way to avoid conclusions they swallow without remorse in similar intellectual situations. I am saying that (other) atheists mistake their own disinterest for a sort of proof.

This hardly exhausts the subject. Michael Novak had an interesting post at National Review Online about six different types of atheist which I think is more complete than anything I have written here.
http://article.nationalreview.com/?q=MTVmYWIyYTI3MDNkMjQxNWJkZjBjNDQyNDI2YThiNmQ=