This is not to say immoral acts are inexcusable, all people must be held responsible to what, at the time and place, is considered immoral/illegal according to society...which, by the way is relative. Which society sets the standard? All are different. You mean the society that has the most power to enforce its brand of morality? I will tell you now that morals will not make sense if they are manmade - relativism is full of holes and there is no way to plug them.
That is why they are relative...how would you know if a moral issue was man-made...would it depend on your personal interpretation of the word of God?