Let me give my view of atheism as a positive view of the world:
Misunderstanding #1:
Atheists do not believe in God. They are a spiritual vacuum waiting to be filled.
Agnostics do not believe in God. Atheists believe that there is no God. The distinction between these two positions is not subtle semantics, it is a fundamental difference. I believe that God does not exist. This is a positive belief, not a lack of belief. You can try to convert me to your belief system if you want, but I'll try just as hard to convert you to my beliefs - and I'm giving you fair warning, I have converted people to atheism before. Different atheists have different reasons for believing that God does not exist. Personally, I first came this conclusion for reasons similar to those that Jake expounded here recently - there are too many religions. Almost invariably, people believe the religion of their parents because there is no good reason to choose one religion over any other. Why should my religious beliefs be an accident of my birth? And, no matter which religion you choose, most of the people in the world will think that you are wrong. Better to choose none. As I learned more about the world, I learned that there is no good reason to believe in any God and found many other reasons to believe that there is none.
Misunderstanding #2:
Atheists do not believe in Hell, therefore there is no reason for them to behave morally -they can do whatever they want.
Atheists behave morally because they understand the difference between right and wrong, just like most other people. The difference between right and wrong arises from biology (kill people like you and you are killing the same genes that exist in your own genotype; engage in incest and you degrade your own genotype), economics (people do not get rich by stealing; crime-ridden economies are poor economies), and common sense (if you make the world a bad place, then you'll spend your life in a bad place). I don't believe that Christians, Muslims, or anyone else actually avoids sin because they are afraid of Hell. I think they avoid sin because they know the defense between right and wrong. Because religious people do not trust others to do what is right, they use Hell to try to scare them into behaving morally (which does not work) and to scare them into converting (which sometimes does work). Furthermore, I don't believe that Christians are any more moral than anyone else - look at the divorce rate in the Bible belt (highest in the country); Catholic priests abusing children; I personally know a United minister who was defrocked for embezzling from the poor box; etc.; the list of immoral Christians is too long to enumerate, but may actually be longer than the list of immoral atheists by the following logic. If I wanted to do evil things, and could ignore or rationalize my fear of God, then I would join the strictest church that I could find, sit in the front pew, and sing the loudest, the better to convince people to trust me while I cheated, swindled, and hurt them. Thus, the set of observant Christians may include both the sincerely devout, who are just as moral as the average atheist, and the evil parasites that want to prey upon them, who are considerably less moral than the average atheist.
Misunderstanding #3:
If this world is all we have, then why bother to do good works for others.
The motivation to do good works is exactly because "this is all we have". I see Christians (and other religions, I'm not singling out Christians, they're just the most prominent group here) idling their time away on Earth, waiting for heaven. To paraphrase Watt, Reagan's first Secretary of the Interior, "there's no reason to preserve the Earth because Armageddon is coming soon and we're all moving on to Heaven anyway." The atheist's logic is that we have to make things better here because this is the basket that holds all of our eggs. No sense wasting time preparing for the next life because there ain't one. And there's no sense praying for God to make things better here, because He ain't there to hear you. We have to make this into the best world that we can all by ourselves. So far, we've done a pretty good job of it. Despite what the pessimists say, the world is a better place to live today than it was a hundred or a thousand or ten thousand years ago. And there's every indication that we can make it even better for our great grandchildren if we work at it. Our grandparents were practical people who build a better world for us and we owe it to our grandchildren to do the same.
Thus, IMHO, Atheism is a religion with a more positive outlook than the alternatives.
Yours,
Thom