Internally, Atticus faces conflicts such as Atticus vs. passivity. Atticus's sister comes to stay with him and the kids and proceeds to begin running the household. During this time, Atticus struggles with his desire to avoid conflict. The kindness he shows people is often a great asset, but when his sister comes, Atticus must combat the tendency to please everyone in order to maintain some control over his household. This is seen when Atticus goes to scold Jem and Scout but then changes his mind and decides that his children do not need to follow the propriety that Aunt Alexandra outlined.
"This was not my father. My father never thought these thoughts. My father never spoke so. Aunt Alexandra had put him up to this, somehow."
The above quote shows Atticus's internal conflict with trying to please everyone. However, Atticus ultimately decides against enforcing Alexandra's words and tells the children,
"I don’t want you to remember it. Forget it.”
These quotes also show an external conflict that Atticus faces between himself and his sister.
Externally, Atticus faces Atticus vs. society when he goes to trial on behalf of Tom Robinson. This conflict is between him and the town of Maycomb. Because of the pervasive racism, Tom Robinson will likely be convicted of a rape that he obviously did not commit. Atticus takes the case and decides to defend Tom Robinson to the best of his ability, despite most of the town's gossip and judgement. One night, Atticus has to face a mob that includes a man named Mr. Cunningham. This mob wants to kill Tom Robinson. A quote that supports this conflict is as follows:
"Mr. Cunningham’s basically a good man," [Atticus] said, "he just has his blind spots along with the rest of us." Jem spoke. "Don’t call that a blind spot. He’da killed you last night when he first went there."
This shows that Atticus is in conflict with the ideology of racism as well as the actual men who threatened Tom Robinson.