a good starting place for any philosophy is an extension of what numerous species already have in place, empathy. it is alluded to in biblical scripture, do unto others, etc, which is sound game theory in any group of any animal, reciprocal behaviour, it's in an individuals interest to be nice to others in a group or they will be cast out from it, this is certainly true in most of our cultures, but this philosophy, while recognised by jesus, didnt come from him. it's been around a whole lot longer than him, and in more species than just ours. Put simply, when you do something that will or may affect others, put yourself in their shoes and think about whether you'd want it done to you. That produces sound morality, whether it's source is religious or not.