Redemption is a major theme in The Kite Runner, and so there are many possible thesis statements to choose from. The first thing to do is read the book and decide which character is most deserving of redemption, and who actually achieves it at the end. The eNotes study guides will also help with their character, theme, and plot analyses.
For example, in the beginning of the novel, Amir witnesses bullies abuse his childhood friend, Hassan. Instead of trying to help, he runs away. Later, he finds out that Hassan was his half-brother and decides to get Hassan's own son out of Afghanistan. A simple thesis statement could read: "Amir's redemption comes when he saves Hassan's son." A more elaborate one could read: "Hassan represents Amir's failure as a boy, while Hassan's son represents Amir's redemption as an adult."
Amir's father, Baba, also acts as a figure of redemption; while he treats Amir with some distance as a child, he later shows great courage in defending a woman from rape. This thesis could read: "Baba, who is found to have committed adultery, redeems himself by saving another woman from rape."
Finally, Rahim Khan is the catalyst for Amir's redemption; he tells Amir about Baba and Hassan, and Hassan's son. This thesis could read: "Without Rahim Khan's involvement, Amir could never have redeemed himself." Another thesis could read: "Rahim Khan receives his own redemption through Amir, since neither could achieve it on their own."