Contradiction with Matthew 10:33
This verse states that whoever denies Jesus before men, Jesus will also deny before His Father in heaven, contradicting the implication of possible forgiveness or acceptance after denying Jesus as seen in Peter's story in John 18:27.
Matthew 10:33: But whosoever shall deny me before men, him will I also deny before my Father which is in heaven.
Contradiction with Matthew 26:34
Though not a contradiction in event, it reiterates the certainty of Peter's denial, which is a prophesied event, while John 18:27 presents it as happening, highlighting the contradiction between prophecy and free will.
Matthew 26:34: Jesus said unto him, Verily I say unto thee, That this night, before the cock crow, thou shalt deny me thrice.
Contradiction with Luke 9:26
This verse mentions that being ashamed of Jesus leads to Jesus being ashamed of the person in the presence of God, conflicting with the eventual restoration of Peter after his denial in John 18:27.
Luke 9:26: For whosoever shall be ashamed of me and of my words, of him shall the Son of man be ashamed, when he shall come in his own glory, and [in his] Father's, and of the holy angels.
Contradiction with Mark 8:38
This verse claims that if anyone is ashamed of Jesus, He will be ashamed of them when He comes in His Father's glory, contrasting with Peter's ultimate role and forgiveness after his denial in John 18:27.