My Atheism: The benefits of morality...

Preface: I was recently challenged by a blogging/email buddy to explain my atheism and I responded, rather reflexively, with curt answers.  The questions were good ones, if not just a bit vehemently posed.  This post is one of a short series that attempts to answer those inqueries in a more respectful way.  Two disclaimers though: a) The questions were posed as a set and therefore have a certain coherency.  At the risk of losing the thread, I have decided to separate the individual parts and offer a post on each.  I have preserved the original order of the questions in the order of the posts if you choose to reconstruct the original query, b) I have, in some cases, edited the question to tone down the sarcasm.  These qestions were posed in the heat of "battle", and in order to reduce the chance of my responding in kind and missing the important points, I have tried to responsibly restate the question in the spirit in which it was originally intended.  Any mis-treatment in this respect is my own error and I apologize in advance, although I have made an effort to maintain my civility. 

Question 2a) If you don't believe you have an 'existence' beyond this life, what is the benefit of ANY morality? 

Response 2a) I like the definition of morality used by Stan Slap in his business book "Bury My Heart at Conference Room B" wherein he proposes that "Morals" or "how a person ought to act in the opinion of authority, consensus or the popularly interpreted rules of society" are " the right thing to do".  This definition is similar to that posed in the Oxford New American Dictionary that morality is a set of "principles concerning the distinction between right and wrong or good and bad behavior".  It seems to me that any community that hopes to survive will require rules to maintain and sustain itself and its members.  I see morality as a social imperative.  So, I guess the short answer to Question 2a is that I don't believe in an afterlife, and morality keeps us alive and ensures the perpetuation of the species.  That seems like a benefit to me.