A Threat?

In the picture above, Peter holds a knife while talking to Mary/John. Catholics suggest that it was likely a butter knife, and Peter has his hand on John's shoulder because he was getting his attention before talking to him. Perhaps he was even holding him up, because it looks as if he's about to faint. Dan Brown, however, has a different take on it. He believes that Peter has a menacing look on his face, and suggests that Peter was threatening Mary Magdalene, which would explain the startled look on Judas's face. Since the Gospel of Philip says that disciples were jealous of Mary Magdalene because Jesus loved her more than the others, it is possible that Peter- who even Catholics admit had problems with Mary Magdalene- was acting on this jealousy. According to Brown's theory, Christ has just told the group that Mary would continue his dynasty after his death, rather than one of the disciples, so the idea that what's going on here is a threat directed at Mary Magdalene would make sense.