In western Christian theology, describes how human beings can be reconciled to God through Christ's sacrificial death. Atonement refers to the forgiving or pardoning of sin in general and original sin in particular through the death and resurrection of Jesus, enabling the reconciliation between God and his creation. Within Christianity there are, historically, three or four main theories for how such atonement might work:

• Ransom theory/Christus Victor (which are different, but generally considered together as Patristic or "classical", to use Gustaf Aulen's nomenclature, theories, it being argued that these were the traditional understandings of the early Church Fathers);
• Moral influence theory, which Aulen considered to be developed by Peter Abelard (called by him the "idealistic" view);
• Satisfaction theory developed by Anselm of Canterbury (called by Aulen the "scholastic" view);
  • The penal substitution theory (which is a refinement of the Anselmian satisfaction theory developed by the Protestant Reformers, especially John Calvin, and is often treated together with the satisfaction view, giving rise to the "three main types" of atonement theories - classical or patristic, scholastic, and idealistic - spoken of by Aulen).