In the novel, To Kill a Mockingbird, the mockingbird represents innocence. When Atticus says to his children, “Remember it’s a sin to kill a mockingbird,” Scout muses, “That was the only time I ever heard Atticus say it was a sin to do something,” implying that killing an innocent creature was not only against man’s law, but against God’s as well.
Like the bird, Tom Robinson is also an innocent creature. His only intention was to be helpful and hard working man. He was targeted, not for his character, but for his appearance. Young Jem might want to kill a mockingbird, because like most young boys of his time he liked to shoot, but his father warned him to distinguish between the innocent “mockingbird” and the guilty “bluejay.”
Interestingly, Harper Lee intimates that there is an appropriate time to kill. Just like Atticus giving permission for Jem to kill the nest-stealing bluejay, so Lee assents to the killing of Bob Ewell by Boo Radley. Ewell represents bigotry, child abuse, and falsehood. Boo Radley, though not a completely innocent character like Tom Robinson, is vindicated by what he does, because he saves Scout’s life.