Atticus's Journey takes him to the dark side of Maycomb. Through his controversial stance he sees more of the racism and that not everyone is as rational as he is. That they'd go as far as to murder children just to get back at him for attempting to defend a black man.
Rescue from Without
Atticus is never physically attacked, but his children are. Jem's arm is broken and he's knocked out. Atticus never suspects he's dead, but Scout keeps asking "is Jem dead".
Master of Two Worlds
Scout and Jem hold Atticus up on a pedestal. They believe he can do no wrong and that he knows everything. Atticus sees this behavior and recognizes he has a responsibility to be a good role model That's one of the main reasons he took the case, because he has to show Jem and Scout that everyone should be treated equal in the eyes of the court.
Freedom to Live
During the trial it seems the odds are impossibly stacked against Atticus. He's trying to defend a black man in a small southern town. The other lawyer has physical evidence (Mayella's injuries), and the word of two white people against a black man. But just when all hope seems lost Atticus swoops in with the fact that Tom Robinson couldn't have injured Mayella because of his crippled hand. He also got Mayella to basically admit her dad abuses her and was the one who hurt her.
Atticus conquered life in both the "familiar" and the "unfamiliar". Even though he lost the case, the black community is hugely receptive to him, they even cook food for him and leave it at the door step. And after the trial most of the town still has great respect for him.
The problem is resolved, Atticus no longer represents a black man. It is not a happy ending considering Tom was killed, but in the end Maycomb's problem with Atticus no longer exists. Atticus didn't just show the town everyone is equal in court, he also taught his kids a valuable lesson. He taught them to do what's right no matter what and to find common ground with your enemies.