At the beginning of the novel, it is evident that Jem and Scout Finch have a great deal of respect, admiration, and love for their father Atticus. By the end of the novel, he becomes more than just a character, but a hero to the readers of the novel as well. Harper Lee has Atticus emerge from just a character in a book to a beloved character in our hearts by showing us that all of his words, thoughts, and actions are those of a person worthy of admiration.
Atticus loves humanity, and believes that all human beings are worthy of respect and dignity. This is evident in the way he treats his children, Calpurnia, the Cunninghams, the Robinsons, and even the Ewells. Even though he is a lawyer and fairly affluent compared to most people in the county, he doesn't expect any preferential treatment. When Jem invites Walter Cunningham, Jr. over for lunch, Atticus discusses farming issues like he is speaking to a grown man. When Atticus is defending Tom Robinson, he takes and builds his case like it was any other man in town.
Atticus is an admirable character because his insides match his outsides. He doesn't just say that he believes all people are equal. His behavior indicates that he believes that as well. People in town may not always like what he has to say, but they know he'll be fair. He always does the right thing with the right intentions, even when the results are not ideal. He knew before he took Tom's case that he was going to lose, but it didn't stop him from doing the right thing.
Atticus has stamina. Even though that trial was brutal on his family, he saw it through to the end. Losing the trial didn't discourage him for long, either. He was able to see that the jury taking so long to deliver its verdict was a step in the right direction. It wasn't a large step, but it was a step, and he was encouraged by it. His perseverance is evident in the way he's parented his children alone all these years, his ability to deal with his sister Alexandra's obnoxious ways, and especially how he dealt with Bob Ewell and his attack on Jem and Scout at the end of the novel.