Well.... I have that old book, you know, which tells me.
Nah, just kidding.
Seriously now... I don´t have an objective rule to differate between good and evil. Did you not listen? Did you not read me previous posts? I explicitly said that "...you cannot objectively define [...] 'good' or 'evil'. "
You do it subjectively. Based on your feelings, your education and upbringing, your social setup, your personal hopes and goals. And, referring back to my last post, your basic fact of being human.
Missed your edit the first time.
Rules come from the interaction of individuals. People are diverse... but not THAT diverse. They are all people. They are all humans, sharing the same basic needs and wants and a lot more not so basic stuff.
The only system of morals that is at least partially objective is utilitarism. Set a goal and see if an action / behaviour is suitable for achiving that goal or hindering that goal. Based on that objective evaluation you can define "good" and "evil"... but only for the actions in question. You cannot make an objective statement about the morality of the ultimate goals.