Reliability of Mark's Gospel

One challenge to Mark's gospel is the claim that it is not reliable due to being written long after the events by a non-eyewitness. However, it is defended that Mark was written within living memory of the events it records and is based on eyewitness testimony, particularly that of Peter. The early figure John the Presbitter attests to Mark being the interpreter of Peter who wrote down accurately what he remembered of Jesus' teachings and actions. Additionally, the literary relationship between Mark and Luke suggests that Mark was written earlier than Luke, likely in the AD 50s.