"...He knows things no one is supposed to know, like how Jesus made alcohol when his mother asked him to."
GREAT question. The answer is straight-forward. John was an apostle, and one of Jesus' closest friends (along with Simon Peter and James). In other words, he was an eye-witness and participant in the work of Jesus during his earthly ministry. The Gospel of John is Jesus' story from John's point of view, so what you're reading in your Bible is not based on the testimony of people that weren't there. It's based on first-hand, eyewitness accounts. Even if John did not witness specific events personally (e.g. Jesus' mother asking him to help during the wedding of Cana, John 2), he interviewed eyewitnesses that were present. A reliable and honest author in the Greek and Roman world drew from reliable sources. That's what John did! In fact, we could surmise that Jesus actually told John in conversation what he did during the wedding feast. That's how he wrote about what happened in John 2.
[Answered by Pastor HM]
