Synopsis: The Monday before Easter, in a three-hour primetime event, ABC News will try to get at the real story of Jesus and Paul, two men who, against all odds, changed the course of human history.

The first century was barely 30 years old, and Rome ruled the world from Europe to the heart of the Middle East. The Caesars were gods and most people knew nothing about a young Jewish peasant named Jesus of Nazareth, who preached on the edge of the Roman Empire.

When Jesus died on the cross, he left behind a small and frightened group of followers struggling to make sense of his humiliating end. Most Jews either rejected his message or ignored it. As noted scholar and best-selling author Karen Armstrong says in Jennings' report, "If anyone had said this is a great idea for a new religion, a man who died a disgraceful death of a common criminal in an obscure province of the Roman Empire who is in some way divine, people would have laughed in your face!"

Yet within a few decades, and against all odds, the tiny Jesus movement began to spread and, in spite of ridicule, suspicion and persecution, would ultimately displace the Caesars, as well as the mystery religions and pagan cults that crowded the Roman world. Paul did perhaps more than anyone to make that happen, even though he never knew Jesus. After Jesus' death and resurrection, Paul becomes the main character in the Bible story about the birth of Christianity.

According to the Bible, Paul had a sudden conversion on the road to Damascus, and began preaching the stories of the crucifixion and Jesus' resurrection in a way that was appealing to a broad audience. Were it not for Paul, says Armstrong, "Christianity probably would have remained a small sect within Judaism." The program includes the perspectives of a wide variety of biblical scholars -- secular and religious, Christian and Jewish, liberal and conservative.

Both conservative and liberal scholars agree that it was Paul who first articulated the ideas we have about the Jesus who was sent by God to die in order to redeem the world's sins. The letters Paul wrote as he traveled the Roman Empire form the basis of the religion that today we call Christianity. Ironically, Paul "never anticipates that 20th century Americans are going to be his audience," historian Pamela Eisenbaum tells Jennings. "He has no idea, because he thinks the world is going to end."

Paul, who is a central figure in the New Testament, is as controversial today as he was in the first century. His words are read from pulpits throughout the world every Sunday. But scholars tell Jennings that, in Paul's own day, he fought bitterly with the closest friends and family of Jesus, who all had a different vision for their fledgling movement. Paul is described by some as a madman and by others as a genius. He is the author of the famous "Hymn of Love" read at modern Christian weddings.

But he is also the man blamed for centuries of anti-Semitism. The program looks at the fairness of such characterizations, as it traces Paul's role in turning Christianity into a religion that was distinct from Judaism.

"Peter Jennings Reporting: Jesus and Paul - The Word and the Witness" takes viewers back to a time and place when Christianity was but a tiny movement struggling for survival, telling the story of two men -- Jesus and Paul - who had remarkable faith, iron will and a radical vision.

Without them, Christianity as we know it today would not exist. Both sacrificed everything in the belief that God had chosen them to change the world. And they did.

ABCNEWS.com will feature companion programming, including a comprehensive interactive map and timeline of Paul's journey, a gallery of images, web-exclusive articles, more about the scholars i