I think that Rahim Khan's quote about what true redemption and atonement involve is a great opening to a speech. Invoking the idea that "true redemption is when guilt leads to good" can help to establish how one of the major element of the novel is how individuals are able to address the evil things they have done in their past. I would focus my speech on the opening of the novel. The phone call that opens the narrative is one that stresses that there is a way "to be good again." This helps to establish the idea that individuals can atone for the evil things that they have done in their past if there is acceptance and understanding present.
I think that being able to focus on how Amir is able to go back to Afghanistan in recognition of the wrong he has done is critical to the theme of atonement in the novel. Focusing on how he confronts his past, willingly sacrifices for Sohrab, and becomes them moral structure that is absent in the world is a part of this atonement process. Another aspect of this atonement could be seen in Baba, who learns to become a better man and father only after leaving Afghanistan. The novel shows that an essential part of being in the world is the ability to recognize sins and transgressions and rectify these conditions in the world. Emphasizing these characterizations can help in enhancing the quality of the speech regarding atonement and acceptance of individual wrong in the course of The Kite Runner.