BOB ABERNETHY, anchor: Now, the legacy of Abraham. Muslims, Jews, and Christians all tell the Abraham story, with its chilling account of God's command to Abraham to kill his own son. Today, scholars for the three faiths are examining their common and different understandings, hoping that will help bring Middle East peace. But a central problem turns out to be religious claims to the land of Israel: Jews say it is theirs because God promised it to them, through Abraham; Muslims say they are entitled to it because they are the more faithful. Mary Alice Williams tells the story.

MARY ALICE WILLIAMS: One man changed all of human history with a simple, radical idea: there is only one God. And in return, according to Genesis 12, God promised, "I shall make of you a great nation and all the families of the earth shall bless themselves by you."

Yet Abraham's progeny have written his name in blood and hatred ever since. Abraham is the spiritual patriarch of half the people alive today. Jews, Christians, and Muslims, in battling over his paternity, have each wreaked havoc in an attempt to commandeer his legacy.

Abraham's story is just that. A story. There is no concrete archaeological or scientific evidence that he even existed. But what a story: a 75-year-old man with a barren wife who is promised not only a child, but a whole nation and a land that will be his legacy.

Abraham heeds God's call, in Hebrew "Lech Lecha": "Go forth from your father's house and go to a land which I will show you." Homeless and childless, he journeyed in the desert where his wife, Sarah, offered him an Egyptian slave, Hagar, who bore him a son, Ishmael. Then Sarah conceived her own son, Isaac, and Hagar and Ishmael were sent into the desert.

BRUCE FEILER (Author): But this is the key moment. God says it's okay for Abraham to do that because he will continue to bless Ishmael.

WILLIAMS: Bruce Feiler wrote ABRAHAM: A JOURNEY TO THE HEART OF THREE FAITHS as a way of trying to comprehend the religious enmity that led to September 11.

Mr. FEILER: God will bless Isaac. Isaac will get the land. God will also bless Ishmael. God is trying to bless all humans. He does it through both children.

The children may not be able to get along with each other, but they both get along with God. And I think in a way, it's harder for people to argue over God. It's easier to argue over Abraham. And he who controls Abraham, controls God.

WILLIAMS: The Jewish Torah and the Qur'an have parallel stories of Abraham. For the Jews and Christians, Isaac inherits God's blessing. For Muslims, Ishmael is the chosen son. In Genesis 22, God commands Abraham to sacrifice his son. All three religions revere Abraham's most spectacular test of faith. For Christians, that prophesied the crucifixion. Professor Walter Brueggemann of Columbia Theological Seminary.

Professor WALTER BRUEGGEMANN (Columbia Theological Seminary): In John 3:16, that's quoted in football games and so on, that God so loved the world that he gave his only son. That is a fairly direct appeal to Genesis 22. That then was taken up by Christians to sort of make the case for Jesus as the fulfillment of the Abraham tradition.

WILLIAMS: Jews see the sacrifice as a test of Abraham's faith in God; Muslims see it as a test of his submission to God. Jews say Isaac was the son to be slaughtered; Muslims say it was Ishmael. Imam Omar Abunamous is the spiritual leader at the Islamic Cultural Center in New York.

Imam OMAR ABUNAMOUS (Islamic Cultural Center): God tests everybody in order to make sure that we are sincere and loyal to him or not, whether we believe in him or not. So God put Abraham face-to-face with a very hard exam.

Mr. FEILER: But the point is that it's about a father attempting to kill a son -- it's a violent act. Abraham is not only the legacy of peace and blessing, but also for violence. That you can fight wars over God, that you can run crusades, that you can fly planes into buildings, that you can kill yourself in the service of killing other people -- everything that is going on the front page of the paper today, violence in the service of faith begins with Abraham.