Comparing the account of the Transfiguration in Mark and Matthew, I noticed some intriguing differences in the two endings of the narrative.
Mark 9
“Elijah will indeed come first and restore all things, yet how is it written regarding the Son of Man that he must suffer greatly and be treated with contempt? 13 But I tell you that Elijah has come and they did to him whatever they pleased, as it is written of him.” (story ends here)
Matthew 17
12 I tell you that Elijah has already come, and they did not recognize him but did to him whatever they pleased. So also will the Son of Man suffer at their hands.” 13 Then the disciples understood that he was speaking to them of John the Baptist. (story ends here)
The question is, why does Mark omit the statement "Then the disciples understood that he was speaking to them of John the Baptist." I've been studying Mark carefully in recent days and I've noticed that this gospel often takes a dim view of the disciples, who consistently fail to understand Jesus. For example:
6:51 He got into the boat with them and the wind died down. They were [completely] astounded. 52 They had not understood the incident of the loaves. On the contrary, their hearts were hardened. (In Matthew 14:31-33 their hearts are not hardened, instead they worship Jesus as the Son of God.)
8:29 And he asked them, “But who do you say that I am?” Peter said to him in reply, “You are the Messiah.” 30 Then he warned them not to tell anyone about him. (in Mark, Peter does not add "the Son of the living God" after "Messiah" and Jesus does not give him the keys to the kingdom as he does in Matthew.)
9:31 He was teaching his disciples and telling them, “The Son of Man is to be handed over to men and they will kill him, and three days after his death he will rise.” 32 But they did not understand the saying, and they were afraid to question him. (In Mt 17:22-24, they understand well, and they are "overwhelmed with grief.")
The question: how should we understand Mark's omission of "then the disciples understood..." in Mark 9? Does it represent a pattern in Mark (more affirming of Paul's theology/authority) compared to Matthew's (more likely to affirm the authority of Peter the original apostles)? If not, how should one explain the omission in Mark 9 and his other seeming denigrations of Peter and the apostles?