Under the mythicist paradigm, the Christians who were unaware of the concept of the historical Jesus could consider a ''degrading heresy'' (so the happy term of Robert M. Price) that new concept introduced the first time by the first Gospel (Mark or Mcn: a pauline Gospel in both the cases).
Therefore the victims of the first Gospel had to be precisely the anti-pauline followers of the Pillars: the Petrine Christians. Their ''fault'', when they read Mark the first time, was to have preached, until that moment, a Christ not known by them.
Someone among them did choose to correct Mark by writing Matthew. But surely other Petrines rejected the entire concept of a historical Jesus, since they did prefer to continue the preaching of the original mythical Christ. Their expected and more natural answer could only be: WE DON'T KNOW WHO IS THIS JESUS OF NAZARET.
Then Peter should be considered innocent and not a liar, in this episode:
When Peter ''began to curse'', he was really cursing the historicist concept of Jesus, in that moment. The irony of ''Mark'' (insider) is that Peter is to be condemned even if he was saying the truth (that he didn't know a Jesus from Nazaret).While Peter was below in the courtyard, one of the servant-girls of the high priest came by. 67 When she saw Peter warming himself, she stared at him and said, “You also were with Jesus, the man from Nazareth.” 68 But he denied it, saying, “I do not know or understand what you are talking about.” And he went out into the forecourt.Then the cock crowed. 69 And the servant-girl, on seeing him, began again to say to the bystanders, “This man is one of them.” 70 But again he denied it. Then after a little while the bystanders again said to Peter, “Certainly you are one of them; for you are a Galilean.” 71 But he began to curse, and he swore an oath, “I do not know this man you are talking about.” 72 At that moment the cock crowed for the second time. Then Peter remembered that Jesus had said to him, “Before the cock crows twice, you will deny me three times.” And he broke down and wept.