Accusations against Jews were a common pretext for massacres and expulsions throughout the Middle Ages in Europe. Similar accusations were made in witchcraft trials; the witch-hunter's guide Malleus Maleficarum refers to Hosts as being objects of desecration by witches. It is part of many descriptions of the Black Mass, both in ostensibly historical works and in fiction.
Roman Catholic, Orthodox, and some Anglican Churches believe that during the celebration of the Eucharist, the offerings of bread and wine are changed into the literal body and blood of Jesus. In the Middle Ages, Catholic theology offered the concept of transubstantiation to explain this change, believed to be actual and not merely symbolic. The concept, defined as a dogma at the Fourth Lateran Council of 1215, holds that the substances of the offerings are transformed, while the appearance of bread and wine remain.
As Christians believe Jesus to be "true God and true man", his body and blood in the form of the consecrated host are adored in the Catholic Church. Theft, sale, or use of the host for a profane purpose is considered a grave sin and sacrilege, which incurs the penalty of excommunication, which is imposed automatically in the Latin Rite (See Code of Canon Law, Latin Rite Code canon 1367, or Eastern Rite Code canon 1442.) It was widely believed that under certain circumstances, such as disbelief or desecration, the host could display supernatural properties.
Some Protestant denominations, especially Lutherans, have similar beliefs regarding the Eucharist and the Real Presence, though they differ about the rite and the concept of transubstantiation with Catholics and Orthodox Christians.
Host desecration has been associated with groups identified as inimical to Christianity. It is a common belief that desecration of the host is part of Satanic practice, especially the Black Mass. The modern Church of Satan regards Christian doctrine as false, and does not desecrate the host in most rituals. Satanists do not typically perform Black Mass as a regular ritual, though "Le Messe Noir" from Anton LaVey's work The Satanic Rituals does include some elements.
Since the publication of a document called Memoriale Domine in 1969, the Apolistic See of the Catholic Church has allowed certain countries to allow communicants to receive the Host in the hand, rather than directly onto the tongue, reviving an "ancient custom". Communion in the hand is now widespread in many parts of the world. The practice means that access to consecrated Hosts is easier than in the past, since the person receiving it in the hand may pretend to place it in their mouth for consumption.
Accusations of host desecration leveled against Jews were a common pretext for massacres and expulsions throughout the Middle Ages in Europe. At the time, the concept of Jewish deicide — that the Jewish people were responsible for the death of Jesus — was a generally accepted Christian belief. It was claimed that Jews stole consecrated hosts and desecrated them to re-enact the crucifixion of Jesus by stabbing or burning the host or otherwise misusing it. These accusations may have been based on the paradoxical belief that Jews considered the host the literal body of Jesus; by crucifying it they imagined they were crucifying Jesus anew. They were believed to use blood that flowed from the host to get rid of the "fœtor Judaicus" ("Jewish stink"), or to color their cheeks to give them a fresh and rosy appearance.
In some variants of this libel, the stabbed host would shed drops of blood. This idea may be based on the natural phenomenon because scarlet colonies of a Serratia marcescens (also called for this reason Micrococcus prodigiosus) may sometimes form on stale food kept in a dry place, bearing similarity to drops of blood. Later variants appear to further vilify Jews, depicting them as burying the host in an attempt to hide it, rather than converting. Where the host was buried, a new spring burst forth from the ground. In one instance, Jews were said to be burying pieces of a pierced host in a meadow; it then transformed into butterflies that healed cripples and blind persons. In another example, angels and doves flew out of a stove in which Jews were burning the desecrated host. Again, the pieces fluttered out of a swamp, and a herd of grazing oxen, on seeing them, bowed down before them. The blood from the host was said to have splashed the foreheads of the Jews, leaving an indelible mark that betrayed them.
Variations in the claims aside, Jews in the Middle Ages were frequently victims of similar accusations, considered more serious desecration of other revered items, such as relics or images of Jesus and the saints. The accusations were often supported only by the testimony of the accuser, who may potentially bear a prejudice against the accused Jew or the Jewish people. Despite this, some alleged perpetrators were tried and found guilty, on little evidence or through torture.
The penalties for Jews accused of defiling hosts were severe. False confessions were coerced by torture, and accused Jews were condemned and burned, sometimes with all the other Jews in the community, as happened in Berlitz in 1243. in Prague in 1389, and in many German cities, according to Ocker's writings in the Harvard Theological Review. According to William Nichol in Christian Antisemitism, "over 100 instances of the charge have been recorded, in many cases leading to massacres."
The accusation of host desecration gradually ceased after the Reformation when first Martin Luther in 1523 and then Sigismund August of Poland in 1558 were among those who repudiated the accusation. However, sporadic instances of host desecration libel occurred even in the 18th and 19th century. In 1761 in Nancy, several Jews from Alsace were executed on a charge of host desecration. The last recorded accusation was brought up in Bislad, Romania, in 1836.