Rahim Khan in Khaled Hosseini's The Kite Runner

What is the thematic significance of the quote from Rahim Khan in Khaled Hosseini's The Kite Runner, "There is a way to be good again"? My brother is having difficulty with his literature class, I would need help to make him pass this essay. They had been reading "the kite runner" and based on the book the teacher assigned essays topic for them. Since our first language wasn't English, so we are not really fluent and good at it.