Atticus resists gender stereotypes by discussing the trial of Tom Robinson with Scout. Specifically, he gives Scout a definition of what constitutes rape, which is one of the crimes with which Tom has been charged. That said, Atticus uses a pretty legalistic definition of rape, referring to it as "carnal knowledge of a female by force and without consent," an expression that Scout doesn't really understand.

Nevertheless, the very fact that Atticus is even discussing this matter with his daughter is quite unusual for the time. As Atticus points out, women aren't allowed to sit on a jury; this is presumably to spare them the sordid details of serious crimes such as rape. And before the trial of Tom Robinson gets underway, a motion is considered in court to prohibit women and children from attending proceedings. One can see, then, how Atticus's discussion of the case with Scout really does represent a challenge to traditional gender roles.

Atticus' lack of gender stereotyping is obvious in how he raises his children. He treats Jem and Scout as equals; when he asks Jem to look after Scout, he does so not because Scout is female but because she is considerably younger than Jem. He never expects Scout to defer to Jem because he is a male member of the household. Also, Atticus cares about Scout's education as much as he cares about Jem's, teaching her to read long before she started school.

Atticus knows Scout is in a tomboy stage of her life and it bothers him not at all. Aunt Alexandra, however, harps constantly that "Jean Louise" (never "Scout"), must be taught to dress and comport herself as a little lady. Atticus listens but does not change Scout's daily lifestyle. Scout recalls that when Alexandra would call her into the living room to meet the ladies of Maycomb, Scout's appearance always caused consternation:

When I appeared in the doorway, Aunty would look as if she regretted her request; I was usually mud-splashed or covered with sand.

Atticus is not concerned with Scout's dress or daintiness; he cares instead that she, like Jem, grows into a strong, compassionate, just, and responsible adult. 

Atticus does not force gender stereotypes upon his son, either. During the terrible events of Tom Robinson's trial, Jem was often upset and sometimes heartbroken. He sometimes shed tears of anger, frustration, and pain when witnessing the racism and injustice that surrounded him. Atticus was sensitive to Jem's feelings, never scolding him for his tears or telling him to "act like a man." Atticus treated each of his children as individuals deserving of respect, as well as love.

In To Kill a Mockingbird, how does Atticus Finch resist the prejudice that is displayed throughout the novel?

Atticus deviates from the stereotypical prejudicial behavior of the white old south in many ways. First of all, he defends Tom Robinson. And while he was appointed to do so, it was always his option not to defend Tom as he should have. That is, he could have written Tom off as a "lost cause," or defended him with less enthusiasm because of his color, but Atticus defended him just as if he were anyone else; black or white, it made no difference. This display of colorblind objectivity is one way that Atticus defies the prejudice of his setting.

In To Kill a Mockingbird, how does Atticus Finch resist the prejudice that is displayed throughout the novel?

Atticus Finch is the epitome of passive resistance throughout the course of the novel. The only time his feathers seem to be ruffled is when he learns that his children were attacked by Bob Ewell.  He is a strong, stoic figure, who faces the problems of the novel with a quiet intelligence.  He does not fight with his fists, but with his words.  He tells his children to not engage, particularly rambunctious Scout, in any sort of fight, even when children call their father "n-- lover" and make fun of them for their father's defense of Tom Robinson. When Bob Ewell spits in Atticus' face, Atticus simply wipes away the spit and calmly states "I wish Bob Ewell didn't chew tobacco."  When facing the angry lynch mob coming for Tom, Atticus stands firm, no harsh words nor aggresive heroic gestures.