Note: for Rabbi Gellman's article, see Trying to Understand Angry Atheists.
Rabbi Marc Gellman compares his opinion on the existence of the Judeo/Christian god with sports fans' love for their teams. The difference is that even the most rabid fan knows that there are other teams and wouldn't dream of forcing his opinion on everyone else — even on people who don't like sports. It would be ludicrous for people to do this and outrageous for the government to encourage it. If this occurred some citizens would get upset or angry, especially if they discovered that the team that everyone is supposed to root for doesn't even exist. No one has ever actually seen this team, but most people seem to like believing in it because it makes them happy and gives them meaning.
Most Atheists that I know are quite content living without the threats and enticements of a god we see as imaginary. We gain meaning from love and a well-lived life that can include helping others and working for a better world. We don't want other people's religious beliefs intruding into our government or our lives. We know that we are responsible for our behavior, and life is to be lived and treasured, not spent waiting for some illusory afterlife. We don't have the debasing idea that we are intrinsically sinful. We realize that Atheism is the simple conclusion that no gods exist, based on evidence and logic. Gods are just the external manifestations of both our base and good emotions. The supposedly sacred scriptures attributed to these gods similarly reflect the strengths and weaknesses of humankind.
Atheists see god belief/religion as the excuse or source of some of the most heinous actions in history — slavery, the Crusades, the Inquisition, the executions of "witches," the prosecution and execution of scientists and free-thinkers, the many European religious wars, the Holocaust, and of course 9/11.
Atheists know that fear and greed were at the root of those terrible things. Many also understand that enlightened self-interest and evolution-derived innate feelings have encouraged most humans to cooperate with our neighbors and to love our mates and children. Any ancient humans who didn't cooperate or love would have been less likely to survive in a tribe or leave offspring. Any humans who did cooperate and love would have been more likely to leave offspring. Evolution is the source of cooperation and love, not mandates from some god.
Morality and laws are the rules of interaction that allow us to function cooperatively. They come from basic human kindness, compassion, and our need to work together — not from some static scripture. Morality and laws have evolved as humans have evolved our culture.
Rabbi Gellman is correct in concluding that it's important to accomplish goals of improving the world. What's most important, I believe, is how we treat each other, not (as Dr. Watson noted) whether we believe in a god. We can all love and care for each other — if we so choose.