I believe this conversation between Socrates and the respected religious pagan authority Euthyphro sheds some light on the answer. Socrates is surprised to find that Euthyphro is prosecuting his own father for murdering a slave. Euthyphro says he did so out of piety (i.e., holiness or righteousness). So Socrates asks him to define what is pious (i.e., holy or righteous):
Euthyphro. Piety, then, is that which is dear to the gods, and impiety is that which is not dear to them.
Socrates. Very good, Euthyphro; you have now given me the sort of answer which I wanted. But whether what you say is true or not I cannot as yet tell, although I make no doubt that you will prove the truth of your words.
Euth. Of course.
Soc. Come, then, and let us examine what we are saying. That thing or person which is dear to the gods is pious, and that thing or person which is hateful to the gods is impious, these two being the extreme opposites of one another. Was not that said?
Euth. It was.
Soc. And well said?
Euth. Yes, Socrates, I thought so; it was certainly said.
Soc. And further, Euthyphro, the gods were admitted to have enmities and hatreds and differences?
Euth. Yes, that was also said.
Soc. And what sort of difference creates enmity and anger? Suppose for example that you and I, my good friend, differ about a number; do differences of this sort make us enemies and set us at variance with one another? Do we not go at once to arithmetic, and put an end to them by a sum?
Euth. True.
Soc. Or suppose that we differ about magnitudes, do we not quickly end the differences by measuring?
Euth. Very true.
Soc. And we end a controversy about heavy and light by resorting to a weighing machine?
Euth. To be sure.
Soc. But what differences are there which cannot be thus decided, and which therefore make us angry and set us at enmity with one another? I dare say the answer does not occur to you at the moment, and therefore I will suggest that these enmities arise when the matters of difference are the just and unjust, good and evil, honourable and dishonourable. Are not these the points about which men differ, and about which when we are unable satisfactorily to decide our differences, you and I and all of us quarrel, when we do quarrel?
Euth. Yes, Socrates, the nature of the differences about which we quarrel is such as you describe.
Soc. And the quarrels of the gods, noble Euthyphro, when they occur, are of a like nature?
Euth. Certainly they are.
Soc. They have differences of opinion, as you say, about good and evil, just and unjust, honourable and dishonourable: there would have been no quarrels among them, if there had been no such differences-would there now?
Euth. You are quite right.
Soc. Does not every man love that which he deems noble and just and good, and hate the opposite of them?
Euth. Very true.
Soc. But, as you say, people regard the same things, some as just and others as unjust,-about these they dispute; and so there arise wars and fightings among them.
Euth. Very true.
Soc. Then the same things are hated by the gods and loved by the gods, and are both hateful and dear to them?
Euth. True.
Soc. And upon this view the same things, Euthyphro, will be pious and also impious?
Euth. So I should suppose.
Soc. Then, my friend, I remark with surprise that you have not answered the question which I asked. For I certainly did not ask you to tell me what action is both pious and impious: but now it would seem that what is loved by the gods is also hated by them. And therefore, Euthyphro, in thus chastising your father you may very likely be doing what is agreeable to Zeus but disagreeable to Cronos or Uranus, and what is acceptable to Hephaestus but unacceptable to Here, and there may be other gods who have similar differences of opinion.
classics.mit.edu/Plato/euthyfro.html
What I learned from this dialog is why Monotheism is more logical than Paganism: The Pagan gods cannot possibly all be wise, because they are like you and I–they disagree on morality. Therefore, there must be another source of wisdom besides them. That source of wisdom was the God above all pagan gods that Socrates himself said he worshiped in Plato’s *Phaedo *and in other dialogs. Some say that Socrates was the first Greek Monotheist.
