Jesus' death and resurrection underpin a variety of theological interpretations as to how salvation is granted to humanity. These interpretations vary widely in how much emphasis they place on the death of Jesus as compared to his words. According to the substitutionary atonement view, Jesus' death is of central importance, and Jesus willingly sacrificed himself as an act of perfect obedience as a sacrifice of love which pleased God. By contrast the moral influence theory of atonement focuses much more on the moral content of Jesus' teaching, and sees Jesus' death as a martyrdom. Since the Middle Ages there has been conflict between these two views within Western Christianity. Evangelical Protestants typically hold a substitutionary view and in particular hold to the theory of penal substitution. Liberal Protestants typically reject substitutionary atonement and hold to the moral influence theory of atonement. Both views are popular within the Roman Catholic church, with the satisfaction doctrine incorporated into the idea of penance.