Although hatred of the Jewish people had been a part of Christianity from its inception, the full virulence was not felt until the end of the 11th Century. During the high Middle Ages, Christian anti-Jewish passion reached its zenith. So strong was the anti-Semitism that many of the attitudes Christians developed regarding Jews clearly led hundreds of years later to the Holocaust – and are still widely felt today.

Early Christian Anti-Semitism

With the triumph of the Church during the reign of Constantine, for the first time Jews found themselves in a wholly Christian world. The Church, believing that Judaism was a rival to Christianity, saw many enlightened pagans and Christians attracted to the Jewish faith. Indeed, from the early contact between Jews and Romans hundreds of years before, there had been a stream of converts to Judaism throughout the empire, at times reaching considerable proportions. Unlike the pagan Roman empire, which was generally tolerant in matters of religion, the new Christian Roman Empire claimed to represent the only true faith – meaning that Judaism, and Jews, were an anathema.

In the Fourth Century, Constantine decreed that Jews could not prevent their co-religionists from converting to Christianity, and could not accept converts. Another law affected Jewish slave owners, stipulating that if a Jew circumcised his slave in accordance with Torah law, the slave gained his freedom. Later, the death penalty was prescribed for circumcision. In later centuries, Christian Roman law forbade Jews from holding public office or officers’ rank in the military.

Theologically, the early Church Fathers laid the groundwork for much of subsequent Christian anti-Semitism. St. John of Chrysostom, known as "The Golden Mouth" for his eloquence as a preacher, called the Jews "godless, idolaters, child-murderers, [guilty of] stoning the prophets, and committing ten thousand crimes." Gregory of Nyssa added that Jews are ”Murderers of the lord, assassins of the prophets, rebels and detesters of G‑d, companions of the devil, [a] race of vipers, darkeners of the mind, Sanhedrin of demons, accursed, detested, enemies of all that is beautiful."