This article is to address "what sin is" along with other related themes, such as guilt and weakness, from the Christian point of view and point out the differences between "sin" and "guilt." It is of paramount importance to help people distinguish between guilt and the real commitment of sin, but we should first see the differences between the healthy guilt and the unhealthy guilt. The unhealthy guilt has impact not only on personal interplay but also on one's relationship with God. The cure of the unhealthy guilt is about making one understand that their parents would still love and forgive them even if they make mistakes. In Christian faith, similarly, God would hate their sins but still love them, which will make them change. The ritual practice of Christian shepherding and the process of spiritual counseling and companying will help them understand God's love, guide them to reconcile with themselves, others and God, relieve them of guilt and regain their internal freedom.