Dear Professor Dawkins,
I have watched several of your documentaries and discussions with great interest. I am regularly taken aback by the willful ignorance of some of those people you are talking to and the "arguments" that they present. Although you regularly come out on top, it seems to me that you could have done better in refuting one particularly outrageous claim.
In these discussions religious people regularly insinuate that atheists have no moral guideline. According to them there should be blood running in the streets where I live with ~80% atheists (Halle an der Saale, Germany). Of course this is not the case, indeed quite the opposite is true: when the worst flood in over 400 years hit my hometown in early June 2013, they had to announce on the radio that people should stop bringing food for the countless volunteers because there was already more than enough to go around. No looting, no rioting, no shooting as people with questionable morals might have done.
Instead of pointing out the immoral passages of the bible to those zealots you should have provided hard facts about the world we live in today. If you compare the countries of the world there is a trend that more secular countries tend to have lower homicide rates, which can be vividly illustrated by superimposing the two sets of data on a world map. Of course this correlates with other factors such as economic prosperity and such, but it seems that religious morality has failed to pacify violent crime hot spots.
As for the need for an absolute moral standard, I can't see one. People have been and will be able to act on a rather basic set of moral principles that they internalized when they were a child and negotiate the rest through an ongoing discourse. The contributions of Mead, Blumer, Luhmann and other sociologists shed more light on the process of human interaction than any religious text I know of.
So maybe next time you argue with those who cannot be reasoned with you can try to provide them with current case studies, statistical data, and a theoretical framework that was not written by ancient herdsmen.