I just saw the movie and two thumbs up!
Looking back at the movie, I think the innocent black fellow that got sent to prison and almost killed represented Christ. Lee, as the rest of us, sent Christ to die even though he was innocent.
There are two lines in the movie that the black man was given that stick out in my mind. The first was when Lee originally met the black man to question him with the assumption that he was guilty. Half way through the conversation the black man stops him and gets up and says as he begins to walk away, "No, we are done here, You have already made up your mind."
Then at the end of the movie Lee goes to visit the black man in the hospital after he had been savagely beaten, and should have died. He gets into his ear and says, "I'm sorry I did not believe you". To which the black man said, "That's because you didn't want to believe it.".