By Candida Moss and Joel Baden, special to CNN

(CNN) - Last week a video of Hamas spokesman Osama Hamdan emerged in which he claimed that Jews use the blood of non-Jewish children to make matzo for Passover.

The translation of Hamdan’s interview with the Lebanese television station Al-Quds on July 28 reports him as saying:

We all remember how the Jews used to slaughter Christians, in order to mix their blood in their holy matzos. This is not a figment of imagination or something taken from a film. It is a fact, acknowledged by their own books and by historical evidence. It happened everywhere, here and there.

When confronted about his statements by CNN's Wolf Blitzer on Monday, Hamdan did not retract his claim or distance himself from the blood libel slur. His only defense was that he “has Jewish friends.”

Whatever “historical evidence” or “facts” Hamdan believes himself to be remembering, this is nothing more than the infamous blood libel: the most persistent and longest-lived anti-Semitic myth in history, aside from the claim that the Jews killed Jesus.

The blood libel originated in medieval England with the death of William of Norwich. William was a 12-year-old tanner’s apprentice who was killed in 1144. At the time of his death, his parents accused the local Jewish community of responsibility, but investigations revealed nothing.

Six years later Thomas of Monmouth, a Benedictine monk, decided to investigate and sensationalize the murder.

Drawing purely on anti-Semitic hearsay and sensationalism, he wrote a martyrdom account, "The Life and Miracles of William of Norwich," in which he said local Jews, acting as part of an international conspiracy, crucified the young boy as part of a ritual to reclaim control of the Holy Land.

Monmouth’s work was used to garner financial support from pilgrimages to the boy’s grave and laid the foundations for the blood libel.

Similar stories crop up throughout Europe in the Middle Ages, often accompanied by episodes of violence and retaliation toward Jews. Stories of mob lynchings and illegal trials abound, especially during the Crusades, when these stories were used to justify pogroms.

In the case of the disappearance of 2-year-old Simon of Trent in March 1475, the entire Jewish community was arrested and 15 men burned at the stake after being forced to confess under torture. Until 1965, Simon of Trent was regarded as a saint in the Catholic Church.

Throughout history the specifics of the blood libel varied and expanded. It primarily involved the baking of Christian blood in Passover matzo, but early accounts also occasionally described the crucifixion of children, the poisoning of wells, and the use of Christian blood to heal cuts from circumcision.

It should go without saying that these lurid stories in all their manifestations are patently untrue.

But these accusations of ritualistic murder and cannibalism are found not only in anti-Semitic propaganda. Early Christians faced their fair share of slander, too.

The Christian writer Minucius Felix records one rumor, which spread widely in the second and third centuries, that early Christians would ritually kill and consume infants as part of their initiation rites.

These accusations are effective because they strike at the heart of society’s fears about outsiders. They involve the most vulnerable (children), the destruction of public resources (wells), or the presence of secret organizations in society's midst.

Accusing those who are religiously different of attempting to undermine society by engaging in the ultimate taboo of cannibalism provides a justification for dislike of and violence toward small nonconformist groups.

But the shadows of history are long, and the longevity of this particular slander is impressive.

As recently as 1928, Jews in Massena, New York, were victims of blood libel. And in 2005, 20 members of the Russian Duma attempted to ban all Jewish organizations on the grounds that Jewish groups were anti-Christian and practiced ritual murder.

References to the Nazis are irresponsibly bandied about in modern discourse, but in the case of blood libel these myths helped sow the seeds of the Holocaust.

In his interview Hamdan linked blood libel to current events in Israel.

He said, “The Israelis concentrate on killing children. … This is engraved in the historical Zionist and Jewish mentality, which has become addicted to the killing of women and children.”

Blood libel is only one chapter in the violent history of anti-Semitism, but it resurfaces throughout as a means of encoding anti-Jewish sentiment and justifying violence toward and mistreatment of Jews.

As Osama al-Baz, an adviser to former Egyptian President Hosni Mubarak, observed in 2013, some “Arab writers and media figures … attack Jews on the basis of … racist fallacies and myths that originated in Europe.”

Hamas may be doing no more than repeating tired cultural clichés and long-debunked slander, but myth and action go together. The history of Europe is a testimony to the devastating power of the blood libel.

People and cultures are defined by the myths they create, but also by the myths they accept and propagate.

Joel S. Baden is professor of Hebrew Bible at Yale Divinity School. Candida Moss is a professor of New Testament and early Christianity at the University of Notre Dame.