The story of Abraham and Isaac that is read on the second day of Rosh Hashana is one of the most problematic in the Torah. How can God ask Abraham to perform an immoral act and would Abraham really have done it? Fortunately we know at the very beginning that this is a trial, a test, and that God will not permit Isaac to be sacrificed.
Nevertheless the story is not a simple one to deal with. The question also arises: why is this read on Rosh Hashana and referred to in the High Holy Day liturgy? We know that human sacrifice, and especially the sacrifice of a first-born, was not unknown in Abraham's time. Was Abraham therefore not surprised at the request? His whole attitude, his silence, indicates that he was. Furthermore it would not be a test if there were nothing difficult about it for him. (Nevertheless the fact that it was done by others must be kept in mind.)
What purpose does the story serve? The Torah makes it obvious that it is intended as an explanation of why Abraham was singled out by God and was worthy of the promise of the land. See Genesis 22:16-18 where God says that since Abraham has done this, He will bless him and grant him the land. Abraham demonstrates his complete trust in God. Perhaps his trust was that God would never require him to do something immoral.
It has been suggested also that this story was aimed at the pagan world which might say: we are willing to sacrifice our children for our gods, what about you? To which the Torah answers: Abraham would do so, but that is not what God wants. Another purpose served, and it is an important one, is to teach that human sacrifice is not the will of God and thus to eliminate it from true religion.
As told in the Torah the story should be entitled "The Trial of Abraham." The midrash, however, retells the story in quite a different way as "The Binding of Isaac" (Akeidat Yitzhak) and it is as Akeidat Yitzhak that it is connected to Rosh Hashana. These midrashim, found in various collections, the earliest of which originated sometime in the 1st and 2nd centuries CE, used the ancient story in order to deal with two matters that were of current concern. One was the martyrdom that Jews were undergoing during the period of Roman persecution. The other was the Christian narrative that taught that the sacrifice of Jesus, his death on the cross, was necessary for salvation and the forgiveness of sin. Christians saw in the Isaac story the precursor of the crucifixion. Later Christian art commonly depicted Isaac carrying the wood in the form of a cross.
For the midrash, the binding of Isaac demonstrated that the Christian doctrine was incorrect and superfluous. Whereas in the Torah Isaac is totally passive, in the midrash he becomes the hero of the story. He is an active participant in his own martyrdom, and thus becomes the symbol of martyrdom for all Jews. He knows his fate and agrees to it.
As Shalom Spiegel has shown in his magnificent book The Last Trial, some versions even go so far as to indicate that Isaac was actually slain, his blood and ashes offered on the altar, after which he was restored to life again. Because of Isaac's sacrifice and Abraham's willingness to suppress his own inclinations in order to fulfill God's command, God is prepared to forgive sins. This was the Jewish answer to the Christian claim: There is no need for the sacrifice of Jesus. Isaac's story had preceded it by centuries and rendered it unnecessary. The midrash concludes, "In the future Isaac's children will certainly sin before Me and on Rosh Hashana I shall judge them. If they want Me to find merit for them and remember the binding of Isaac, let them sound the shofar before Me and I will save them and redeem them from their transgressions" (Midrash Tanhuma Vayera).
The shofar, which has no specific meaning in the Torah, becomes identified with the horn of the ram caught in the thicket. Blowing it invokes God's forgiveness because of the merit of the sacrifice of Isaac. The genius of the rabbis was their ability to take a story whose original meaning was no longer relevant and transform it in such a way that it dealt with the burning issues of their time.
Unfortunately the question of martyrdom did not cease with the Romans, and the theme of this story became actual again during the Middle Ages when many piyyutim were written on this theme. The medieval Jewish martyrs saw themselves as the Isaacs of their time, called upon to die, not because God willed it, but for the sake of kiddush hashem - sanctifying God's name by going to the stake rather than giving up their religion. In this way the ancient story became and remains relevant, even if the questions it raises can never be answered completely.
The writer is the head of the Rabbinical Court of the Masorti Movement and the Rabbinical Assembly of Israel.