Nancy Weaver writes to Shaka, because she's the godmother of Chris, the man Shaka killed.
Astonishingly, she lets Shaka know that she forgives him. She describes her pain and struggles and some of the challenges Chris's family has gone through, but she also assures Shaka that she has forgiven him. She also genuinely seems to believe that Shaka can change.
In her case, this forgiveness and hope stems from her faith in Christ. Even though Shaka moves away from Christianity, he is really thankful for Nancy's forgiveness. Shaka writes back, and they correspond. It takes about five years for Shaka to start changing in the way Nancy hopes for, but it really happens.
Shaka shares the story and her letter in the Afterword as an example of a person with remarkable hope…and he asks the rest of us to share that hope.