Original sin is the Christian doctrine that humans inherit a tainted nature and a proclivity to sin through the fact of birth. Theologians have characterized this condition in many ways, seeing it as ranging from something as insignificant as a slight deficiency, or a tendency toward sin yet without collective guilt, referred to as a "sin nature", to total depravity or automatic guilt of all humans through collective guilt.
The doctrine of original sin began to emerge in the 3rd century but only became fully formed with the writings of Augustine of Hippo (354–430), who was the first author to use the phrase "original sin" (Latin: peccatum originale). Augustine's conception of original sin was based on a mistranslated passage in Paul the Apostle's Epistle to the Romans, and scholars have debated whether the passage supports Augustine's view.
Augustine's formulation of original sin became popular among Protestant reformers, such as Martin Luther and John Calvin, who equated original sin with concupiscence (or "hurtful desire"), affirming that it persisted even after baptism and completely destroyed freedom to do good and proposed that original sin involved a loss of free will except to sin. Modern Augustinian Calvinism holds this view. The Jansenist movement, which the Catholic Church declared heretical from 1653, also maintained that original sin destroyed freedom of will. Instead the Catholic Church declares "Baptism, by imparting the life of Christ's grace, erases original sin and turns a man back towards God, but the consequences for nature, weakened and inclined to evil, persist in man and summon him to spiritual battle." "Weakened and diminished by Adam's fall, free will is yet not destroyed in the race."