The god debate really has little to do with this. Selfish/Selfless is a false dichotomy based on a superficial observation of human behavior.Take a look at the thread I s God A safe Subject. It is related to the selfish and God debate.
Selfishness is a base of human life and no amlunt of religion will erase it.
Or increase it, as everyone fights and struggles to get as much as they can out of this life.I think that no life after death would mean that almost everyone would believe that death is oblivion. With that being the case, many people would want their lives to be the best possible. I truly believe that this would reduce war.