Avoid any person whose ethical code is based upon arbitrary authority. Such people are moral mercenaries, and you cannot trust them except insofar as they remember to believe that God is watching. And they always forget.
• In one of Plato’s dialogues, Socrates questions a man named Euthyphro who is about to prosecute his father for murder. He asks how Euthyphro can be so certain about the nature of justice and piety that he would prosecute his own father for a capital crime. Euthyphro answers that “good” is whatever the gods approved of, while “evil” is whatever the gods despise.* Socrates points out that the gods seem to disagree with each other on such moral questions, and are therefore useless as moral guides. “After all,” Socrates says, “what one god loves, another despises.” (Likewise, what God seems to love in the Jewish scriptures, he seems to hate in the Christian Scriptures — while Islam does nothing to clear up the confusion.) Euthyphro then insists that “good” is whatever all of the gods love, while “evil” is whatever all of the gods despise.
But for Socrates, this only begs the question, “Do the gods approve of what is good simply because it is good, or is it good simply because the gods approve of it?” If it is good simply because it is good, then Goodness is a higher authority than the gods themselves (or God). If it is good simply because the gods approve of it, then it must be irreducibly arbitrary.
But it is absurd to say that good and evil are irreducibly arbitrary. By definition, good and evil are absolutes. Nobody sincerely invokes the notions of good and evil except as absolutes.
• Moral authoritarians, such as Euthyphro, simply delude themselves into believing that moral absolutes can be derived from arbitrary authority. Such thinking finds verbal expression in phrases like: “Homosexuality is a sin! God said it, so I believe it!”
“Do as I say, not as I do.”
or “If you disobey or disbelieve, you will go to hell when you die.”
or “You owe your parents respect and obedience simply because they are your parents.” These are the sentiments of scoundrels whose counterfeit morals serve only to cloak their fear, hatred, and self-centeredness. Avoid them.
* "Good and evil" is not an exact translation, but it's good enough for me.