The name gives a clue - "Redemption" is in the title. The black man gets out of prison differently from Andy. He gives up on trying to prove he is good to the Parole Board. Like the sinner, he gives up and admits his corruption, his depravity.
But Andy leads the way, gives him hope and a way of living after prison. Andy gets out differently. He has to go through 500 yards of sewage. As Christ had to take on, no, become sin for us, taking our shame and filth upon Himself, Andy takes filth upon himself and comes out a new man, with a new identity, with untold wealth. By the way, like Christ, Andy is innocent.
The warden is a Satan figure. He's a hypocrite, a liar, and ultimately a murderer. He persecutes Andy, even though he knows he's innocent. But Andy conquers him in the end, exposing his hypocrisy and ultimately destroying him. And where do Andy and the black man meet at the end? Like Christ and the disciples, who became fishers of men, they meet on the seashore where Andy is working on a boat which he plans to use for charter fishing.
Throughout the movie, Andy is set up in small ways as a Christ figure. Remember the scene where they work on a roof, and Andy gives financial advice (he's a former banker) to the head guard, risking his life in the process. What does he ask for? Beer for his friends. Andy doesn't even drink beer. The black man (played by Morgan Freeman) is the narrator and says he figured that Andy just enjoyed watching them act normal for once.
The prisoners are portrayed as crude and unable to deal with liberty. One who had been in prison for over 50 years, even kills himself because after release, he couldn't handle freedom, no one telling him what to do. We sinners also fear freedom, particularly the freedom of Christ. We ask ourselves, "What will keep me from doing something bad?" We think we need a stick hanging over us to keep us in line. We want someone to tell us what to do. But liberty can judge for itself what is best and can choose God's way. Liberty implies self-responsibility.
Andy is interested in books and ends up helping other guards with their taxes and finances, becoming something of a celebrity among the guards at his prison and even others. Interestingly, Andy keeps a little hammer, the hammer he uses to dig a tunnel for escape, in a book. What book? A bible. The word of God is his key to escape from the slavery the others live in.
Thus, the Shawshank Redemption is really a parable, an allegory, about salvation through Christ.
