Atticus Finch is the most outspoken character in the novel regarding race. Though Reverend Sykes makes some commentary, Atticus delivers a number of lines regarding race, racism, and racial prejudice in the novel. He mentions racial biases when he speaks about newspaper editor, and again during the his closing arguments at the trial. 

The most obvious instance is the case of Tom Robinson: the jury's willingness to believe what Atticus calls "the evil assumption . . . that all Negroes are basically immoral beings" leads them to convict an innocent man.

Mrs. Merriweather, in a very different way, employs racist or racially prejudiced langauge at the meeting of the missionary circle. In this scene Mrs. Merriweather discusses the depression, suggesting that it is due to the depression that her family keeps Sophy, their servant working in her house.

The mockingbird motif is mentioned a number of times and is articulated clearly by Miss Maudie. 

It is Miss Maudie who affirms that it is a sin to kill a mockingbird, since "they don't do one thing but sing their hearts out for us."

One of the novel's statements regarding courage comes from Atticus when he discusses Mrs. Dubose and her struggle to free herself from a morphine addiction. 

Here Atticus defines one of his views of courage:

"It's when you know you're licked before you begin but you see it through no matter what..."

As a novel with a focus on inter-related themes, and as a novel directed toward an audience of young people, the themes are often reiterated and given direct expression. For this reason, the quotes above are not all of the examples of the articulation of the novel's themes.