This is the best "Why I am an atheist" essay in PZ's blog. It includes the best definition of faith I have ever seen.

Why I am an atheist – Heather Dalgleish

I am an atheist, in short, because I am a rationalist and a scientist. I am an atheist because of reason – because of a simple love of the power of reasoning and rational thinking to bring real clarity, resolution and a grasp of the closest thing you really will get to get to real ‘truth’ while living out your lives on this pale blue dot. (Or indeed while living anywhere else in the cosmos – to any readers tuning in from the International Space Station, Mars, Europa, or wherever.)

I don’t believe in gods for much the same reason that I don’t believe in fairies, bogeymen, ghosts, lucky gems, leprechauns, Santa or the Easter Bunny. There isn’t a shred of convincing evidence for the existence of any of them, plenty of evidence that they are grossly surplus to requirements for explaining any phenomenon, and that proposing them just creates more problems than it solves.

There just isn’t a good reason for believing in any supernatural being, and plenty of good reasons for not believing. Theists who are otherwise rational and who fail to grasp that conclusion are simply not being fully honest with themselves, and failing to challenge their ideas on the subject of gods with the same robustness as they would challenge other ideas. And I speak with experience, as someone who once was that theist.

Indeed, the whole concept of ‘god’ or ‘gods’ is so ill-defined that asking me if I believe in ‘god’ is like asking me if I believe in floogamaloops. I don’t know what floogamaloops are, and neither do you. I don’t know what exactly gods would be like, and neither do you. Or rather, everybody has their own personal idea of what ‘god’ is – varying vastly from person to person, region to region and time to time. To some, god is simply energy, and you can find it in a lump of coal – which is at any rate an interesting insight into the power of wishful thinking, and the tragic lengths some people will go to to cling desperately and shamelessly to this strange ‘god’ notion.

Do you believe immunoglobulin M exists? I do. And I can tell you what it is – and it will be roughly the same definition that any person who knows about the subject will give you. And I could hand you to someone more competent than myself who could give you the robust evidence for the existence of immunoglobulin M, and take you through graceful laboratory techniques that isolate the molecule and allow us to say things about its size, structure and function. The great thing about it actually existing, and having a testable definition, is that it will pass through the fire of reason, and you don’t have to take it on faith. Of course it also helps that IgM is a mere molecule that lacks the capacity to be a passive-aggressive bastard that wants to hide its existence from you, reveal itself occasionally through arbitrary phenomena such as weeping statues and faces in toast, and otherwise must insist on being taken purely on faith – which are common themes on the subject of gods – but let’s not complicate things further.

And that’s why I’m an atheist. My own atheism is a simple consequence of my reasoning – just one result of my mind thinking rationally – one result of many opinions I’ve landed on through reason. And I also know that it’s a stance that some people reach through routes other than reason. Some people are atheists just because they are. Buddhists are atheists, Raelians are atheists – literally anyone who doesn’t believe in gods gets to legitimately call themselves an atheist – no matter how bizarre or outlandish their beliefs and worldviews may be outside of that particular aspect of their thinking. So atheism isn’t important or particularly worthy or noble to me just in and of itself – the process that gave rise to it in my case is. I am an atheist because I am a rationalist – an honest and thorough rationalist – and my rationalism is much, much more important to me than my atheism could ever hope to be.

My atheism is but a small bud sprouting from the scientific thinking that lets me appreciate the real world, the real universe, as it actually is, in every other aspect of my life. Atheism should be one of those things you arrive at in any honest quest for truth – but it’s not an ends in itself. And science, reason, rational thinking and sceptical enquiry are the best tools devised for uncovering reality.

There are of course “other ways of knowing” – it’s just they’re complete bollocks. Beyond laughable in the shadow of empirical science. ‘Intuition’, ‘gut feeling’ and ‘just knowing’ are alternative ways of knowing things, in much the same way that having sex standing up is an alternative form of contraception. Find me a person who could uncover the structure of the atom, of light, of the complexity of life through “other ways of knowing”. It’s exasperating, ridiculous and sad that adult humans can even utter those kinds of opinions with a straight face. I don’t know whether to laugh or cry – and I don’t care if they’re offended by that. They should be. They don’t deserve to be cushioned from having their beliefs poked and prodded – and frankly, they really don’t know what they’re missing by not learning to love sceptical interrogation, the thrill of the culmination of arriving at a real, intellectually satisfying conclusion, instead of evading awkward questions, putting their fingers in their ears and playing the faith card to shield their cherished beliefs.

Faith is by definition belief without evidence – it’s pulling things out of your ass; it’s clinging to things that you might well know are faintly ridiculous; it’s putting up barriers to honest enquiry; it can be used as an impediment to curiosity and intellect, and it is simply the most ridiculous method of discovering or knowing anything about reality. It’s not a virtue – and it shouldn’t be a virtue in wider society any more than it would be in a court of law.

Some atheists of course ‘respect’ such nonsense – but that is just yet another reason why atheism is not an ends in itself to me. It’s all about the process of rationality, reasoning and sceptical curiosity that if pursued boldly should necessarily give rise to atheism, and have much, much broader and deeper ramifications than just mere atheism alone.

Heather Dalgleish
Scotland