Quote 1
"Scout," said Atticus, "n*****-lover is just one of those terms that don't mean anything—like snot-nose. It's hard to explain—ignorant, trashy people use it when they think somebody's favoring Negroes over and above themselves. It's slipped into usage with some people like ourselves, when they want a common, ugly term to label somebody."
"You aren't really a n*****-lover, then, are you?"
"I certainly am. I do my best to love everybody... I'm hard put, sometimes—baby, it's never an insult to be called what somebody thinks is a bad name. It just shows you how poor that person is, it doesn't hurt you." (11.107-109)
In giving Scout a lesson in How Racism Works 101, Atticus also does the same for the audience. On the syllabus in this conversation: the power of language, not only as a way to shame those who don't toe the racist line, but also to set the terms of the debate. Racists use "n*****-lover" to suggest that a person is trying to give African-Americans special rights, but Atticus points out that all he's arguing for is equality, loving everybody the same. The end of the quote is basically a grown-up version of "I'm rubber and you're glue," suggesting that schoolyard taunt actually has some merit—some insults do tell you more about the person hurling them than about their target.
Quote 2
"She was white, and she tempted a Negro. She did something that in our society is unspeakable: she kissed a black man. Not an old Uncle, but a strong young Negro man. No code mattered to her before she broke it, but it came crashing down on her afterwards." (20.44-45)
Question #1: Why do the citizens of Maycomb (or at least some of them) prefer to believe that a black man raped a white woman than that a white woman kissed a black man? Question #2: Why does Atticus use the word "tempted," considering Tom's reaction to her advances seemed less "I totally would, but they'd totally kill me" than "just not that into you, kthxbye"? Isn't this a little racist? Doesn't it imply that, even if Tom can control himself, he wouldn't be able to help being tempted by any white woman?
Quote 3
"Which, gentlemen, we know is in itself a lie as black as Tom Robinson's skin, a lie I do not have to point out to you. You know the truth, and the truth is this: some Negroes lie, some Negroes are immoral, some Negro men are not to be trusted around women—black or white. But this is a truth that applies to the human race and to no particular race of men. There is not a person in this courtroom who has never told a lie, who has never done an immoral thing, and there is no man living who has never looked upon a woman without desire." (20.47-48)
On the one hand, Atticus is totally right: we need to judge people as individuals rather than by their race. No argument here. On the other hand, check out the way he calls the lie of racist stereotypes "as black as Tom Robinson's skin," once again associating evilness with blackness, although in a more figurative way.