Hero conquers villain. We drove the sharp end of the beam into the monster's eye. Hero rejects offer. Jesus did not let him. Hero asks that word of who was responsible be spread.
Hero describes quality of treatment of villain.
Hero sails away. Mark may have left two clues that would signal the reader of his time that he was writing fiction. The second clue is provided where Mark says something that seems out of place. Thus, Mark's message seems to be that after the encounter with Jesus, the man not only is no longer possessed by demons, he is also no longer naked like Polyphemus. I don't believe it helps MacDonald's case to include the incident with Circe.