Here's a summary of the climax:
Revelation of the Trinity:
Papa reveals to Mack that God does not conform to human limitations or traditional religious ideas. Mack recognizes that Papa represents God the Father, Jesus as God the Son, and Sarayu as God the Holy Spirit.
Questioning God:
Mack confronts God directly with questions about the suffering and evil he has experienced in his life, particularly the traumatic memories of his daughter Missy's murder. He expresses anger, pain, and hurt, holding God responsible for allowing such tragedy.
God's Response and Invitation:
God does not offer simple answers or explanations for the suffering. Instead, He gently invites Mack to explore his heart, to see himself and the world from God's perspective, and to accept the reality of both light and darkness in life.
Embracing Forgiveness:
Mack discovers that the key to healing and moving forward lies in embracing forgiveness. He acknowledges his anger and the walls he has built around his heart but chooses to let go and receive God's love and forgiveness.
Spiritual Transformation:
Through the conversation, Mack experiences a profound spiritual transformation. He realizes the depth of God's love and mercy, letting go of his bitterness and finding a renewed sense of peace, hope, and forgiveness.
The climax in "Shack" is deeply emotional and cathartic, bringing Mack's journey of grief, doubt, and despair to a turning point. Through this encounter, he experiences a personal revelation, which paves the way for his healing and reconciliation with both God and his own life.