What is the difference between an agnostic and an atheist?
My father was famously a preacher turned agnostic. We used to argue all the time about the difference between an agnostic and an athiest. I felt the difference was inconsequential, he felt it was important. And I've had the same argument with other proclaimed agnostics. I found an amusing way to sum up my view of it in one answer.
What is the difference between an atheist and an agnostic?
The difference is the atheist says she's an atheist, while the agnostic says she's an agnostic. In other words, the difference is only about what they say and not about what they do. I challenge proclaimed agnostics to describe how their life is different from those who say there's no god, or the even more common "areligious" who simply say they have no religion. (I love Dawkins' answer to those who charge that atheism is a religion -- he says that not believing in god is no more a religion than not collecting stamps is a hobby.)
Some of the argument comes from misunderstandings about how similar the positions really are. Agnostics imagine that atheists say they are "certain" and thus are fools, but the truth is just about every atheist I have ever seen would say that, should God appear before them, miracles a-blazing, they would of course respond to evidence and change their minds. They just don't think it's likely enough to make it worth worrying about. It may be that agnostics do indeed worry about this more than atheists do, which in a way is a difference of behaviour, but a minor one. Atheists by and large admit, in the extreme, that the agnostic is technically right that we can't know for certain, and agnostics, in spite of the claim of uncertainty, live their lives exactly as atheists do, presuming there is no god. Agnostics think the concept of "doubt of certainty" is important. Atheists acknowledge and even agree with it, but find it unproductive.
But in the long run the only difference comes down to what they say, think and worry about, not to what they do. Agnostics that I've met don't tend to pray "just in case" following Pascal's Wager. There should perhaps be a term for those who live their life differently because of that wager, though I will credit some would call themselves agnostic.
It may be the case that agnosticism is a label found almost exclusively in the formerly religious. One doesn't hear much of a person raised atheist (or more simply areligious) who then "converts" to agnosticism, though many convert to atheism and agnosticism from religion.
Some come on, agnostics. Tell me how you live your life differently from atheists. Not how you say or think different things but what you actually do.