Theists often ask me why I care so much about something I don't believe in. When I first started openly questioning supernatural beings, I couldn't answer that question. I knew why, but I just couldn't put it into words yet. The reason is because the claims and actions of theists can be harmful to people, on a psychological and physical level. I don't refute the claims of Bigfoot sightings because while I don't believe in them, I also don't believe that other people believing in Bigfoot will have a negative effect on society in general, or even that person specifically. A belief in god can have profound effects on one's actions and thoughts, cognitive dissonance notwithstanding.
All of that is well and good, but why does this community of people need to have their own label? Well, the only reason there is a need to call attention to the fact that we haven't been convinced there is a god is because there are people out there trying to convince others there is a god. I can't speak for anyone else, but I didn't wake up one day and decide to boycott God Inc.. I don't hate god, the same way I don't hate Bigfoot because I don't believe in either one.
When I really think about it, I can understand why some theists might think atheism is this group that dissenters join when they are mad at god, or if they don't want to be responsible for their actions, allowing them to “live it up” with a clear conscience. Sometimes I hear some atheists speak as if they are speaking for atheists everywhere, and while it bothers me slightly because speaking on behalf of a group indicates that everyone in the group thinks the same way, and possibly because there is a doctrine that says they have to, I can't be too mad because usually atheists only speak in those kinds of terms for wholly accepted truths.
So yes, the word atheist is a necessity. In 100 years, I would hope it won't be. I'd love to just do like the London bus ads say, and get on with enjoying my life, but as long as there are people in the world that want to poison minds and are willing to destroy science in an effort to force others to see the world the way they do, there will be people in the world like me that will be there to enforce honesty and integrity. If we can't get that, then we will point you out as the liars you are. And we'll do it on a global stage. Welcome to the Information Age.