We look at more worldly definitions of right vs wrong, rather than rules handed down by people who supposedly received them from a supreme being. We ask ourselves - "Does this act help the community/society, or does it hurt the community/society?" I think that's how the rules of social contract were originally developed, because there were certainly thriving human societies long before the Bible was constructed. Human dignity (the innate right to be valued and receive ethical treatment) also stems from that.
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