I don't believe John Coffey is as much a Christ-figure as others believe in this thread. Here are the differences I see:
1) Christ didn't want to be crucified (Father, why have you forsaken me?) while John Coffey wanted to die.
2) Christ death and rebirth signified the washing away of the world's sins and salvation for those who accept the gift. John Coffey's death was just tragic in every way.
3) Christ death saved people, a selfless act. John Coffey's death was so that he could be free from the pain he felt as an empath in an ugly world, a selfish act because he could have possibly been freed and went on to continue healing people.
4) Christ taught forgiveness for all, John Coffey punished 2 bad men. I believe that the Wild Bill and Percy deserved what they got and it was for the greater good, but this was not a Christ-like act.
4) Christ gives everlasting life after our lives in this physical realm, John Coffey gave prolonged life on this physical realm. Paul even call what John gave him a 'curse' near the end of the movie.
I believe Coffey was a messenger of God, but not supposed to represent Christ. I think he was sent to ease the transition from slavery up until the civil rights movement of the 1960s.
My hypothesis is that John Coffey was a slave and that's where the scars came from, and he'd been given gifts from God. There were other miracle workers in the Bible who healed people, other than Christ. They used powers given to them by Father God.
I think the meaning of the story is not just about death (death row) but about our relationship with God as we walk through life (The Green Mile(green signifying life) towards our inevitable physical deaths. Are we hurting people along the way (Wild Bill, Percy) or are we helping people as we go (John, Paul, Brutus & the other guards)? Because that's what matters as we walk down the green mile.
I also want to point out that Brutus was the name of one of the assassins who killed Julius Caesar. The man who allowed Christ to be crucified. Not sure what it means but there might be some relevance there.