An interesting question was posed to me, one that I feel every atheist should consider and take the time to respond to - If God is nothing more than a human fabrication then what is there to disprove? Why do atheists spend time arguing about something they don't believe exists?
My personal response is as follows, and though I know for a fact that my response isn't the same as the response others might put forth, I felt it was beneficial to myself to be reminded exactly why I concern myself with what other people believe.
I don't think of myself as wanting to disprove god, I think of myself as wanting to communicate with people of faith to the point where they have to accept that my position has validity. I don't want to change anyone's mind because I honestly don't care - pray to a popple and worship cinnamon toast crunch, it's all the same to me. The issue I see is that there are people in positions of power and influence who use religion to convince the masses of certain ideas which then are put forth as laws with lots of support from said masses. I don't have a lot of money so beyond making phone calls and voting, I can't take an active stand against the people of power, so I do what I can and reach out to people who follow the people of power and try to explain to them why it's wrong to legislate their religion.
I would love to not feel the compulsion to do this and to simply live my happy atheist life, but I can't do that unless other people wake up and realize that belief, even in mass numbers, does not equal a free license to start dictating how others live. I don't go out of my way looking for confrontations or arguments, but I don't back down if I come across them and I rarely ignore them - even if the argument is about something as stupid as whether or not Jesus was a historical figure or if God definitely exists or not. These discussions are less about the subject for me and more about being continually active as yet another voice of atheism. I think, this is stupid to argue about, but maybe if I make enough good points, it'll add to all the other good points this person has heard and they will at least THINK about why they're supporting what they're supporting. Maybe if enough people say they disagree, religious people might stop blindly following that random religious person in a position of influence and start thinking for themselves a little more, and things will get better.
Another reason I willingly engage in conversations and arguments with theists is because I feel like science needs a voice in the everyday world. I am by no means a scientist and I don't have a degree in a scientific field. Most of what I know about science is self taught, and that self taught knowledge is constantly changing with every bit of new evidence which I come into contact with. My point in making this distinction about myself is that I feel like I'm on a level playing field with any random person who is approaching scientific data. I'm not trained in how to read studies and I have trouble at times understanding complex scientific ideas, but the awesome thing about science is that you don't have to be an expert in a field of study to learn more about a particular subject.
You do, however, have to learn to tell science from pseudoscience and I feel like that is an area where a lot of people go astray. It would seem that there is a stigma about science that a lot of my fellow laymen fall into where they feel that if someone has a PhD or a degree in a certain subject that they must know what they're talking about. However, from my experience, it doesn't take an academically trained scientist to distinguish good science from bad. It does take a little bit of effort and skepticism toward what you are reading, especially if you're exposed to an idea which you would like to be true, even though it has been proven false by countless other sources. The argument of whether evolution is real is just as ridiculous to me as the argument of whether god is real, but I still participate in these arguments because though I know the argument against evolution has little to no scientific validity, there are still those people in positions of power and influence telling their supportive masses that evolution is a lie and that preposterous pseudoscientific ideas such as Intelligent Design should not only be taught in schools, but should be taught as science.
This might seem like a huge deviation from the initial question, but it's not. One thing most theists agree on is that for them, god is important in every aspect of their lives. It was, and sometimes still is difficult for me to understand the scope of this kind of thinking as I was never personally religious and didn't grow up with religious parents, but once I understood how truly intrinsic the concept of god is to people, I realized how equally important it was for someone like me, someone who doesn't believe in god, to have their voice be heard.
Misinformation in the name of god is still misinformation, and I feel a personal responsibility to speak out against it wherever it's found. Maybe it's a naive waste of time or delusions of grandeur on my part, I don't know, but at least I'm doing SOMETHING to help spread the word that atheists exist, we're rational people who deserve the same rights as everyone else, and even though people may not agree with us that doesn't give anyone the right to treat us like we count less or don't count at all.