Contradiction with Matthew 11:14
Mark 6:15 refers to Jesus being John the Baptist raised from the dead, while Matthew 11:14 implies John the Baptist is the Elijah who was to come, creating a contradiction in identities.
Matthew 11:14: And if ye will receive [it], this is Elias, which was for to come.
Contradiction with John 1:21
Mark 6:15 suggests John the Baptist returned, but John 1:21 states John clearly denies being Elijah or the Prophet, contradicting the idea of John’s return.
John 1:21: And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. [that prophet: or, a prophet?]
Contradiction with Luke 9:19
Mark 6:15 reports speculation that John the Baptist has been raised from the dead, while Luke 9:19 suggests people thought Jesus might be another prophet instead, causing confusion over Jesus's identity.
Luke 9:19: They answering said, John the Baptist; but some [say], Elias; and others [say], that one of the old prophets is risen again.