<P> Original sin, also called ancestral sin, is the Christian doctrine of humanity's state of sin resulting from the fall of man, stemming from Adam and Eve's rebellion in Eden, namely the sin of disobedience in consuming from the tree of knowledge of good and evil . This condition has been characterized in many ways, 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 something as drastic as total depravity or automatic guilt of all humans through collective guilt . </P> <P> The concept of original sin was first alluded to in the 2nd century by Irenaeus, Bishop of Lyon in his controversy with certain dualist Gnostics . Other church fathers such as Augustine also developed the doctrine, seeing it as based on the New Testament teaching of Paul the Apostle (Romans 5: 12--21 and 1 Corinthians 15: 22) and the Old Testament verse of Psalms 51: 5 . Tertullian, Cyprian, Ambrose and Ambrosiaster considered that humanity shares in Adam's sin, transmitted by human generation . Augustine's formulation of original sin was 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 . The Jansenist movement, which the Catholic Church declared to be heretical, also maintained that original sin destroyed freedom of will . </P> <P> The doctrine of ancestral fault (προγονικὸν ἁμάρτημα progonikon hamartema), i.e. the sins of the forefathers leading to punishment of their descendants, was presented as a tradition of immemorial antiquity in ancient Greek religion by Celsus in his True Doctrine, a polemic attacking Christianity . Celsus is quoted as attributing to "a priest of Apollo or of Zeus" the saying that "the mills of the gods grind slowly, even to children's children, and to those who are born after them". The idea of divine justice taking the form of collective punishment is also ubiquitous in the Hebrew Bible . </P>

When did the concept of original sin begin