In the opening scene of the novel, Amir mentions that his life changed on a cold winter day in 1975. He then says that twenty-six years later, Rahim Khan gave him a call from Pakistan with a chance to atone for his past sins. Amir then walks down to the Golden Gate Park and imagines Hassan's voice whispering, "For you, a thousand times over." That night, Amir thinks about that cold day in 1975 that made him who he was today.
This scene is significant because it foreshadows the main events in the novel. Although Amir does not reveal what happened on the cold day in 1975, the reader understands something took place that dramatically affected Amir's life. The reader also gains insight into Amir's quest for redemption by returning to Pakistan after speaking with Rahim Khan. Throughout the novel, we learn that Amir does not intervene when he sees his best friend getting raped. Amir's actions haunt him for the rest of his life until Rahim Khan presents him with a chance to atone for his sins. Amir's main quest throughout the story is his search for atonement.
The central character, Amir, gets right to the heart of the matter in the opening scene in "The Kite Runner". He describes his memory of "crouching behind a crumbling mud wall, peeking into the alley near the frozen creek". The scene he is remembering is where the defining moment of his life took place. It was in that alley that his loyal childhood friend Hassan was viciously raped while trying to retrieve a kite for Amir's benefit. Amir, a witness to the atrocity, kept himself hidden, and allowed his friend to be victimized without coming to his aid. That moment "changed everything" in Amir's life, and "made (him) what (he) (is) today" - a man who sees himself as being without courage or integrity, a man without honor who would heartlessly betray a friend.
Everything that happens in the narrative is connected to the opening scene described. Amir cannot forget what he did there, and because his sin is hidden, his whole life after that incident is a lie. The phone call he receives from Rahim Khan offers Amir a chance to atone for his transgression, and sets the stage for the central theme of the book. Amir is offered an opportunity for redemption; "a way to be good again" (Chapter 1).