Stories often lend a dimensionality, or even an ambiguity, that cannot be captured through simple codes of law. It is through stories that we gain a sense of how real life events make it very difficult to gain moral clarity.
Take the relationship between Avraham and G-d. G-d says that He is going to destroy Sodom. What does Avraham do? He argues! He negotiates, pushing back against the divine decree with considerable success (the definition of a city worth keeping is dialed back from 50 to 10 righteous people). And we learn that it can be good – and fruitful – to make a stand for what we think is right, even when G-d is saying otherwise! It is, if you like, a celebration of chutzpah.
But when Avraham was told to offer his son as a sacrifice, there was no argument at all! Avraham does not quarrel or quibble.
Traditionally, we ask this question as a means to gain understanding how Avraham’s silent obedience was actually the right thing to do. But what if it was the wrong thing to do? After all, while G-d tells Avraham to sacrifice his son, it is the last time that Avraham speaks with G-d. At the offering of Isaac, G-d speaks through an angel. And that was the last communication with G-d (direct or indirect) that the Torah informs us about.
In other words, obeying G-d may have led to the end of the relationship between Avraham and G-d. Perhaps the test was to see if Avraham could sacrifice his son. Or perhaps the test was to see whether Avraham would, as he had done before, argue with G-d.
Where is the evidence in the Torah for Avraham perhaps making a mistake?
Right after the angel intercedes:
And Abraham lifted up his eyes, and looked, and behold behind him a ram caught in the thicket by his horns. And Abraham went and took the ram, and it as a burnt offering in place of his son. (Gen 22:13)
Consider the following: There are two sacrifices detailed in the Torah for which one brings a ram: For sinning concerning something holy, and for mistakenly violating a commandment.
If any one commit a trespass, and sin through error, in the holy things of the LORD, then he shall bring his forfeit unto the LORD, a ram without blemish out of the flock
And if any one sin, and do any of the things which the LORD hath commanded not to be done, though he was unaware, yet is he guilty, and shall bear his iniquity. He is then to bring to the priest a ram without defect
Both of these apply to Avraham. Isaac was holy, and Avraham sinned with him. And human sacrifice is forbidden, even though Avraham may have been unaware of it.
So when Isaac was not sacrificed after all, G-d arranged for a ram to be found stuck in the thicket, and Avraham offered it as a sacrifice.
But because the Torah is a story, the above is far from definitive. The angel praises Avraham for not withholding his son. Perhaps there were really no good choices.