I feel the need to respond to Ryan's comments because one of the purposes of this site is to de-mystify atheism or at least my own personal brand of atheism which is pretty far removed from Dawkin's. So let’s take them in order
Myth #1. Atheists “know" there is no God.
This is the most common mistake people make about atheists. Because they seemingly claim to know the unknowable, atheists are easily characterized as arrogant and condescending. The problem is that assumes a premise (knowledge of a negative) and a burden (proving a negative) atheist don’t have. People confuse the positive belief in a negative claim (I know that there isn't something) with the lack of belief in a positive claim (I do not believe something). This may seem like splitting hairs but the difference is very important. For example, say I buy a lottery ticket. I don’t know that I won’t win the lottery. But at the same time, it’s perfectly rational not to believe that I will win the lottery. Being an atheist doesn't mean I know that God doesn't exist. It's a big universe and I'd have to be God himself to know that he's not hiding around there somewhere. It just means to me there is a lack of evidence to prove the claim "there is a God".
Myth #2. If you can’t know God doesn’t exist, doesn’t that make you an agnostic not an atheist?
It's often claimed that agnosticism is the only rational position because the existence of God cannot be known one way or another, and therefore one has no choice but to suspend a decision. I'm going to have to call bullshit on that one. If that's true you'd have to be an agnostic about far more than God. After all, no one can "know" for certain that Big Foot, the Loch Ness Monster, and Atlantis don't exist. It is impossible to prove that there isn't a 1978 Dodge Dart orbiting Saturn. No matter how wildly implausible a proposition was, you'd have to give it equal weight as long as it couldn't be disproved. If you were truly agnostic you would lead a pretty interesting life.
Atheism really isn't that complex a philosophy: If you claim something exists, let's see your proof; if your proof isn't very convincing, than I probably won't believe your claim. Sounds nutty I know, but it's worked pretty well for me so far. The mistake that people continually make is to assume it is the burden of the skeptic to prove a negative claim, and if they fail to meet that burden then they have “lost” the augment and we are justified in believing the claim or at least in suspending judgment. This is actually a very dangerous way of thinking.
Let us take the example of the missing WMDs. Bush’s defenders claim he didn't lie when said he stated Iraq had WMDs because he didn’t know that there weren't any WMDs. But of course he did lie because he said there were WMDs when in actuality he didn't know whether there were WMDs one way or the other. In their never ending quest not to appear “biased” the U.S. media got trapped into being agnostic about the WMDs (we don't know he doesn't have them) and fell for the administration's line that it was therefore the burden of Saddam Hussein to prove he did not have WMDs. It was a beautifully ridiculous argument that helped make war inevitable. After all, Saddam could have turned his whole country inside out and that still wouldn't prove he had no WMDs. He could always be accused of hiding them in some new unknown location. In fact, it was the Bush Administration that was making a positive claim (Iraq has WMDs), one that they had the burden to prove, and the proof they had was easily exposed as utter bullshit by anyone willing to do a little digging. If the
Myth # 3: Atheists reject spirituality.
Far from eliminating mystery and uncertainty from life, atheism treats mysteries with the respect they deserve. Life is full of the unknowable and unexplainable. But rather than try to force fit a solution that doesn’t make sense to me, I simply acknowledge them for what they are; things that I don’t know and can’t explain. Rather than giving you all the answers, atheism enlightens you to exactly how much you don’t know. The hardest part of atheism is embracing a level of ignorance that at times can be terrifyingly overwhelming. However, in the words of Socrates at least you know that you don’t know much of anything, and that is a very valuable form of knowledge.
Myth #4: All atheists are materialists
People often assume that if you are an atheist, then you must also be materialist (you are nothing other than the biological functions of your brain). Certainly there are plenty of atheists who do believe exactly that, but not all. I don’t believe in a literal soul, but I absolutely believe that human consciousness transcends biology and physics. I believe in the inexplicability of love, joy, passion, grief, and heartbreak. While they may be biological in origin they are also far more than simply the sum of their physical causes: they are the most existentially real experiences we have, and are what make human beings the weird little evolutionary quirk that we are. However my belief in that transcendence maybe not completely justified from a logical or scientific perspective. In fact it might even be characterized as an act of faith. This leads directly into my next point.
Myth #5: Atheists think everyone else should be an atheist.
Remember all I claimed was that to me there is a lack of evidence to prove the positive claim "there is a God." Some people may have experiences vastly different than mine. Maybe prayer, or meditation, or personal experience leads them to conclude there is a God when they examine all the evidence. I’m fine with that. My two favorite thinkers in the world, people far smarter me and whose influence on me is enormous, were both passionate believers. Atheism is my answer to that question. It’s not the answer for everyone and I personally have no desire to convince anyone else that their belief system is wrong. I’m a firm believer that actions speak louder than words and as long as you’re a good person I could care less what your personal beliefs are.