The word relic comes from the Latin reliquia (in Greek, leipsana agia). Relics of the saints have nothing to do with Vincent Price, Halloween, or the macabre.
They are merely physical reminders of holy people that the Church has officially declared to be saints in heaven. These items have no supernatural powers of their own, and even the miracles performed by the saints to whom these relics originally belonged occurred only by the power of God working through them.
There are three classes of relics: first class, second class, and third class. Unlike the airlines, you cannot get bumped up to first class. First-class relics are any part of the body of saint, usually a small piece of bone. Second-class relics are small pieces of clothing or artifacts the saint personally wore, touched, or used. Third-class relics are anything which was touched by a first-class relic.
Relics were never worshipped, since that would be idolatry and a sin against the first Commandment. They were honored insofar as they were once part of a saintly person, now considered a spiritual hero and friend of God in heaven. The practice began when Christians buried their dead, unlike the pagan Romans who burned theirs. The dead bodies were given Christian burial with the firm and certain hope that at the end of time, when the Second Coming of Christ took place and before the General Judgment of the World, the resurrection of the dead would take place.
So Christians treated the mortal remains of their dead with respect. Roman persecutions lasted three hundred years, during which time Christians hid and worshipped in the very place where they buried their dead: the catacombs. Superstitious Romans were afraid of these graveyards, as they believed them haunted by the dead—good place to hide, then!
When Christianity became legal in 313, thanks to the Emperor Constantine and the Edict of Milan, his mother, Saint Helena, began a campaign to recover as many relics of Christianity as she could get her hands on. She even led an expedition to the Holy Land, and in Jerusalem she found the True Cross of Christ on the hill of Calvary on which the Savior had been crucified and died. This was the largest and most valuable relic known to mankind. She also found the nails that were used to crucify Jesus. Pieces were sent to the patriarch of Jerusalem, the pope in Rome, and the Emperor himself. The rest was left at the Basilica Saint Helena built on the spot.
Tiny slivers of the True Cross have been handed down to various popes, cardinals, bishops, emperors, kings, queens, and other nobility throughout Europe and the Middle East. Sadly, there were some unscrupulous charlatans who sold counterfeit relics to the innocent faithful and, on occasion, there was almost a fever pitch to accumulate as many relics as possible. The church condemned all sales of relics as being the sin of simony and frequently warned people not to base their faith on “things,” but rather on the truth of revelation and on the grace of God.
Nevertheless, some criminal elements made money on the gullibility of a few zealous pilgrims. Many authentic relics today are embedded in altar stones placed inside altars where Mass is frequently celebrated, just as the early Christians used to celebrate in the catacombs.