Outside the courthouse, Mr. Dolphus Raymond sympathizes with Dill about the way white people treat black people without even stopping to think that blacks are people too. Raymond is an eccentric rich white man. He gets little respect from the white people in the town because he's always drunk and lives with a black woman and has fathered interracial children. But Dill and Scout learn that Raymond isn't actually a drunk: he only drinks Coca-cola. Mr. Raymond explains that he fakes being a drunk so people won't bother him for living the way he wants.
Mr. Raymond is another man who sees the evil of racism. But rather than confront it, like Atticus, he hides from the confrontation behind lies.
Atticus is making his closing remarks when Dill and Scout get back to their seats. Atticus notes the prosecution's lack of evidence, then says the courtroom is the one place in America where every man is equal, and asks the jury to "do its duty."
Atticus, in effect, is saying that courts are the only place where a person is granted his dignity and prejudice can be combatted.