We all know the Golden Rule: do unto others as you would have them do unto you. TED Prize Wish winner, Karen Armstrong, even laudably proposed that a Charter for Compassion based on the observation that all three Abrahamic traditions (Christianity, Judaism and Islam) have the Golden Rule at their core.
I do believe that if we all followed the Golden Rule as the basis for how we treat one another the world would be a better place. But I also think there is a a more fundamental rule, call it the Diamond Rule, which is even better:
Treat others as you believe they would want you to treat them, if they knew everything that you did.
The difference is subtle, and may not practically speaking yield different action that often. But when it does, the difference can be significant.