The passage in question reads, "The tombs also were opened, and many bodies of the saints who had fallen asleep were raised, and coming out of the tombs after his resurrection they went into the holy city and appeared to many." This incident took place at the moment of Christ's death on the cross and apparently occurred simultaneously to an earthquake and the tearing of the curtain between the Holy of Holies and the Holy Place (the ante-room to the Holy of Holies).
It is interesting to note the sequence of the events in these verses. First, in verse 50, Christ dies on the cross. Next, in verse 51, the temple curtains are torn from top to bottom. There is an earthquake, the rocks split, tombs are opened, and some of the saints (literally holy ones) are raised from the dead. But notice that they do not leave the tombs until after Christ's resurrection. When they are raised, they go to Jerusalem (the holy city) and appear to many.
JoAnn's question begins by asking who these people are, but the rest of scripture is hauntingly silent on the matter. As she points out, they aren't mentioned again in Acts; they alsp aren't mentioned in any of the other gospels, and after some research, I couldn't find any references to them by the early church writers either. Indeed, it seems as if they never existed outside of Matthew's gospel.
Apparently Matthew had his own source for this event, for neither Mark, Luke, nor John mention an earthquake or any of the other extraordinary events. Why would Matthew include this story?
It is important to remember that Matthew was writing his gospel for a distinctively Jewish audience. He spends a great deal of his gospel showing how Christ fulfilled the prophesies of the Old Testament. As such, Matthew was well aware that the Jewish community awaited the "Day of the Lord" with anticipation, since the Day would bring a new world order with the Messiah ruling and the oppressive Romans would be overthrown.
This Day of the Lord was to be foreshadowed by signs and portents, including the darkening of the sun (Joel 3.15; Matthew 27.45), earthquakes (Joel 2.10; Matthew 27.51), and in some traditions there would be a resurrection of the righteous in Jerusalem. One of the chief objections by the Jewish peoples was that Jesus had not ushered in the Day of the Lord, instead he died on a cross. Matthew, when he wrote his gospel sometime after 50 CE, likely wanted to instill the thought that Christ had indeed ushered in the Day of the Lord, even though it was a thoroughly spiritual kingdom. In so doing he may well have either included details no other gospel writer was interested in including, or else he may have created the account to support the Day of the Lord motif in the Old Testament.
Most scholars agree the historicity of such an event is unlikely. Calvin, in his Institutes claimed the event was included to demonstrate that those saints predating Jesus Christ were included in the realm of Christendom. But before we dismiss the tearing of the Temple curtain, the earthquake, and the resurrection completely, there is one interesting tidbit to consider. Rabbi Yohanan ben Zakkai wrote in the Talmud that the doors to the Temple opened of their own accord 40 years before the fall of Jerusalem, portending the end of the Temple (TB, Yoma 39b). Interestingly enough, the crucifixion of Christ took place 40 years before the fall of Jerusalem as well. A coincidence? If this is historical, perhaps. . . .
If these saints actually were resurrected, in the end their fate would have been the same as Lazarus who, tradition says, died at a ripe old age. Historical or not, the resurrection account in Matthrew spoke of the inclusiveness of God's plan to the world, the wondrous power of Christ, and the truth of his resurrection. May it so speak to us today as well.