“There is a major argument against the historicity [of the Guard Story] that is impressive indeed. Not only do the other Gospels not mention the guard at the sepulcher, but the presence of the guard there would make what they narrate about the tomb almost unintelligible.
The three other canonical Gospels have women come to the tomb on Easter, and the only obstacle to their entrance that is mentioned is the stone. Certainly the evangelists would have had to explain how the women hoped to get into the tomb if there were a guard placed there precisely to prevent entry.
In the other Gospels, the stone is already removed or rolled back when the women get there. How can we reconcile that with Matt’s account where, while the women are at the sepulcher, an angel comes down out of heaven and rolls back the stone? There are other internal implausibilities in Matthew’s account (e.g., that the Jewish authorities knew the words of Jesus about his resurrection and understood them when his own disciples did not; that the guards could lie successfully about the astounding heavenly intervention);but they touch on the minor details of the story.
The lack of harmony with the other Gospels touches on the heart of the story, i.e., the very existence of a guard. Can one save historicity by going back to a preGospel situation and contending that the Jewish Sanhedrin member who buried Jesus, Joseph of Arimathea, may have taken some precaution to protect the sepulcher, and that this developed into the story that Matthew now tells? That is a very hypothetical suggestion, however, for neither Matthew nor The Gospel of Peter connects the guard to Joseph, and even a minor precaution should have left a trace in the other Gospels as an obstacle to the women on Easter.”
–Raymond Brown, The Death of the Messiah, p. 1311-1312