What is "right"?

What is "the right thing" if there is no God given law? Is it something to do with doing the thing that protects and supports community? Why would you do something to benefit community if you were just following evolution's way of looking out for yourself??? Survival of the fittest. Where does benevolence and altruistic behaviour fit into that?? Why do we nurture the sick and disabled?? His way - giving love and kindness without reason - is unexplainable in evolution.

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