The tradition of venerating the relics of martyrs and other saints dates from the earliest years of Christianity. In the fourth century, St. Basil wrote that “by touching a martyr's relics one partakes of the sanctity and the grace they contain.” The Second Vatican Council restated this ancient tradition of the Church: “The saints have been traditionally honored in the Church and their authentic relics and images held in veneration” (Sacrosanctum Concilium, No. 111).
The Church recognizes three classes of relics. A first-class relic is defined as ex ossibus, from the bones of the saint. Second-class relics are clothes and items which belonged to the saint — e.g. a scapular, missal, or rosary. Relics of the third class are pieces of cloth which have been touched against the sacred remains of a saint.
In Rome, during the first century, the tombs of martyrs were kept in the catacombs, a series of underground cemeteries.
The Church required that they not be moved. Later, during the eighth century when the Lombards and the Saracens invaded Rome and set out to destroy the catacombs, it became necessary to transport the remains of the martyrs to safety. The Pope then permitted moving the remains from the catacombs to within the walls of the city.
One of the martyrs' bodies to be moved was that of St. Stephen, who was the first Christian martyr. His relics, which were discovered in Jerusalem around the year 415, began to occasion miracles as soon as they arrived in different European and African cities where they were venerated by the local Christians. Beginning at this time, churches were dedicated to a particular martyr with his or her relics placed under the altar.
Later, the Church placed relics of the saints under every altar where the priest offered Christ's sacrifice. Since 1977, however, the use of relics is not required in the dedication of new churches, although it is highly recommended.
Authenticity of Relics
The Vatican's Congregation for the Causes of Saints determines whether or not a relic is authentic. When a saint is canonized, parts of the saint's body are given over to the Vatican, accompanied by a statement of authenticity by the diocesan bishop or religious superior of the order to which the saint belonged.
Two Augustinian priests are in charge of preparing the small relics for veneration from the remains donated to the Vatican. The Augustinian order has served the papal relic archives since 1352 when Pope Innocent VII created the position. He specified that the position was to be filled by Augustinians because the order had been such great defenders of the papacy.
Until that time some bishops did not investigate the authenticity of relics as thoroughly as they should have. This enabled dishonest men to sell the bones of the ordinary faithful as relics of the early Roman martyrs. Because of these abuses, the authenticity of old relics were subjected to a trial. They were placed under the judgment of God and dropped into a fire. If the relic miraculously survived, then it was held to be authentic.
In addition to the Vatican relic archives, the Holy Father maintains a personal collection, which contains all the relics donated to the popes since the time when Pope Urban VIII started the collection in the 1600s.
— Michael Rose