Penal substitution (sometimes, esp. in older writings, called
forensic theory) is a theory of the
atonement within
Christian theology, developed with the
Reformed tradition. It argues that
Christ, by his own sacrificial choice, was punished (penalised) in the place of sinners (substitution), thus
satisfying the demands of
justice so
God can justly
forgive the sins. It is thus a specific understanding of
substitutionary atonement, where the substitutionary nature of
Jesus' death is understood in the sense of a substitutionary punishment.