This study attempted to describe how religion affects culture, most significantly how it affects undesirable actions such as homicide. It claims to show at least that non-belief does not have a negative affect and at most that it has a positive affect. In some cases I am inclined, however, to believe that the negative affect may promote religion (such as abortion), rather than the other way around. Furthermore it may not be the most reliable study.
http://moses.creighton.edu/JRS/pdf/2005-11.pdf