Atticus represents morality and reason in To Kill a Mockingbird. As a character, Atticus is even-handed throughout the story. He is one of the very few characters who never has to rethink his position on an issue.
His parenting style is quite unique in that he treats his children as adults, honestly answering any question they have. He uses all these instances as an opportunity to pass his values on to Scout and Jem. Scout says that "'Do you really think so?' . . . was Atticus' dangerous question" because he delighted in helping people see a situation in a new light. Atticus uses this approach not only with his children, but with all of Maycomb. And yet, for all of his mature treatment of Jem and Scout, he patiently recognizes that they are children and that they will make childish mistakes and assumptions. Ironically, Atticus' one insecurity seems to be in the child-rearing department, and he often defends his ideas about raising children to those more experienced and more traditional.
His stern but fair attitude toward Jem and Scout reaches into the courtroom as well. He politely proves that Bob Ewell is a liar; he respectfully questions Mayella about her role in Tom's crisis. One of the things that his longtime friend Miss Maudie admires about him is that "'Atticus Finch is the same in his house as he is on the public streets.'" The only time he seriously lectures his children is on the evils of taking advantage of those less fortunate or less educated, a philosophy he carries into the animal world by his refusal to hunt. And although most of the town readily pins the label "trash" on other people, Atticus reserves that distinction for those people who unfairly exploit others.
Atticus believes in justice and the justice system. He doesn't like criminal law, yet he accepts the appointment to Tom Robinson's case. He knows before he begins that he's going to lose this case, but that doesn't stop him from giving Tom the strongest defense he possibly can. And, importantly, Atticus doesn't put so much effort into Tom's case because he's an African American, but because he is innocent. Atticus feels that the justice system should be color blind, and he defends Tom as an innocent man, not a man of color.
Atticus is the adult character least infected by prejudice in the novel. He has no problem with his children attending Calpurnia's church, or with a black woman essentially raising his children. He admonishes Scout not to use racial slurs, and is careful to always use the terms acceptable for his time and culture. He goes to Helen's home to tell her of Tom's death, which means a white man spending time in the black community. Other men in town would've sent a messenger and left it at that. His lack of prejudice doesn't apply only to other races, however. He is unaffected by Mrs. Dubose's caustic tongue, Miss Stephanie Crawford's catty gossip, and even Walter Cunningham's thinly veiled threat on his life. He doesn't retaliate when Bob Ewell spits in his face because he understands that he has wounded Ewell's pride — the only real possession this man has. Atticus accepts these people because he is an expert at "climb[ing] into [other people's] skin and walk[ing] around in it."