What characteristics demonstrate that Atticus is like a mockingbird in To Kill a Mockingbird?
Atticus is generally not considered one of the mockingbirds of the novel; Boo, Tom and the children are the most obvious examples. Atticus is no innocent: He has experienced the loss of his wife, Alabama politics and a Deep South atmosphere that is not friendly towards African-Americans.
However, the previous post points out some excellent examples of how Atticus does fit the term. He has learned to turn the other cheek when insults fly his way, and he does not seek revenge on those who cast them. He allows Bob to spit in his face and he accepts it, he says, if it will spare Bob's children another beating. He is ready for Jem to take the blame for Bob's killing if it will keep Boo out of "the limelight" of publicity. These peaceful attributes are also much like those of the mockingbird.
It is wrong to kill a mockingbird because all they do is make music for people to enjoy. In short, they are don't do anything to hurt anyone.
Atticus does what he firmly believes is the right thing to do, always. He raises his children - and offends Miss Caroline and Aunt Alexandra. He is polite to Bob Ewell and Mrs. Dubose (even when provoked) - and offends Jem and Scout. He defends Tom Robinson wholeheartedly - and offends the town.
Each time someone is offended by Atticus' actions they attack him. Often it is done passive agressively or behind his back, but the intent is the same. The point is to disrespect him and ultimately tear him down. This is the same as "killing a mockingbird."