I want to discuss the difference between definitions and labels. There is a whole population of people who, for one reason or another, refuse to call themselves atheists. Bill Maher and Roger Ebert both come to mind, along with a number of personal acquaintances. To be honest, I can understand their reluctance to embrace the label. "Atheist" is a fairly negative term on its own, and recent popular use has made it even more so. Fair or not (and I think not), the impression of an atheist is an angry, eccentric professor whose disdain for religion is nearly matched by his disdain for humanity in general.
No matter the label, however, there is no denying the definition of the word. Bill Maher, despite his own refusal to claim it for himself, is an atheist. Sure, he is free to call himself "agnostic" because he "doesn't know for sure that god does not exist," but like it or not, if he does not believe in a god, he is an atheist.
In truth, nearly all atheists are agnostics. I can't imagine an atheist who is willing to say with certainty that god does not exist. Most of us shelve the idea of god with Russel's teapot. That is, it is possible but unlikely. Along with that, (and speaking only for myself) since I find the idea of any god highly unlikely, I find the idea of a specific god even less likely. So while I don't think there is any god at all, I think the possibility of the Christian god laughably slim.
As I said, I understand the desire to distance yourself from the label of an atheist. I don't refuse the label myself, but I use it more as a definition, just as one might identify more as a Christian, Catholic, Jew or Muslim, despite the plain fact that they are all also theists. In terms of labels, I like Secular Humanist. It's positive and hopeful, but not loopy or spiritual. I will respect the wishes of all those who do not want to be labeled as an atheist. They should understand, however, that the only two options available are atheist and theist. If they are not one, then they are the other.
*Correction: There are more than two options. There are several, actually. Theists, for example, believe in a god but not a specific, personal god. Polytheists believe in many gods. Pantheists believe that god is everywhere but not specific. These don't invalidate my argument that agnostics are de facto atheists, but I like to be as accurate as possible when making wide, sweeping generalizations.