This is probably the standard question asked by atheists/agnostics. Interestingly, those who ask this question don't seem at all concerned with the existence of other concepts and ideas that they, and their respective societies, live according to. For example, can someone prove to me that Freedom exists? Can someone provide me with evidence that Communism exists? What about Secular Humanism? No, you can't prove to me that all these different concepts exist. Yet, that doesn't stop people from submitting to them, in the sense that it doesn't stop them from basing their moral and social philosophies on said ideas. Cling to Freedom to death and they'll call you a principled martyr. Fight for God and they'll call you a deluded wacko. So, why is God particular scrutinized? I think it's because atheists deliberately equate God to a being, and a being alone. They need to belittle God in order to not take Him seriously. Thus, God is just like Bigfoot or the Toothfairy. He is simply a "creature" that there is no evidence of. Surely, God is greater than that.