quality:correction
Original sin

Augustine taught that the sin of Adam and Eve was either an act of foolishness (insipientia) followed by pride and disobedience to God or that pride came first. The first couple disobeyed God, who had told them not to eat of the Tree of the knowledge of good and evil (Gen 2:17). The tree was a symbol of the order of creation. Self-centeredness made Adam and Eve eat of it, thus failing to acknowledge and respect the world as it was created by God, with its hierarchy of beings and values.

They would not have fallen into pride and lack of wisdom if Satan had not sown into their senses "the root of evil" (radix Mali). Their nature was wounded by concupiscence or libido, which affected human intelligence and will, as well as affections and desires, including sexual desire. In terms of metaphysics, concupiscence is not a state of being but a bad quality, the privation of good or a wound.

Augustine's understanding of the consequences of original sin and the necessity of redeeming grace was developed in the struggle against Pelagius and his Pelagian disciples, Caelestius and Julian of Eclanum, who had been inspired by Rufinus of Syria, a disciple of Theodore of Mopsuestia. They refused to agree original sin wounded human will and mind, insisting human nature was given the power to act, to speak, and to think when God created it. Human nature cannot lose its moral capacity for doing good, but a person is free to act or not act in a righteous way. Pelagius gave an example of eyes: they have capacity for seeing, but a person can make either good or bad use of it.

Pelagians insisted human affections and desires were not touched by the fall either. Immorality, e.g. fornication, is exclusively a matter of will, i.e. a person does not use natural desires in a proper way. In opposition, Augustine pointed out the apparent disobedience of the flesh to the spirit, and explained it as one of the results of original sin, punishment of Adam and Eve's disobedience to God.

Augustine had served as a "Hearer" for the Manichaeans for about nine years, who taught that the original sin was carnal knowledge. But his struggle to understand the cause of evil in the world started before that, at the age of nineteen. By malum (evil) he understood most of all concupiscence, which he interpreted as a vice dominating people and causing in men and women moral disorder. Agostino Trapè insists Augustine's personal experience cannot be credited for his doctrine about concupiscence. He considers Augustine's marital experience to be quite normal, and even exemplary, aside from the absence of Christian wedding rites. As J. Brachtendorf showed, Augustine used Ciceronian Stoic concept of passions, to interpret Paul's doctrine of universal sin and redemption.

The view that not only human soul but also senses were influenced by the fall of Adam and Eve was prevalent in Augustine's time among the Fathers of the Church. It is clear the reason for Augustine's distancing from the affairs of the flesh was different from that of Plotinus, a Neoplatonist who taught that only through disdain for fleshly desire could one reach the ultimate state of mankind. Augustine taught the redemption, i.e. transformation and purification, of the body in the resurrection.

Some authors perceive Augustine's doctrine as directed against human sexuality and attribute his insistence on continence and devotion to God as coming from Augustine's need to reject his own highly sensual nature as described in the Confessions. Augustine taught that human sexuality has been wounded, together with the whole of human nature, and requires redemption of Christ. That healing is a process realized in conjugal acts. The virtue of continence is achieved thanks to the grace of the sacrament of Christian marriage, which becomes therefore a remedium concupiscentiae – remedy of concupiscence. The redemption of human sexuality will be, however, fully accomplished only in the resurrection of the body.

The sin of Adam is inherited by all human beings. Already in his pre-Pelagian writings, Augustine taught that Original Sin is transmitted to his descendants by concupiscence, which he regarded as the passion of both soul and body, making humanity a massa damnata (mass of perdition, condemned crowd) and much enfeebling, though not destroying, the freedom of the will. Although earlier Christian authors taught the elements of physical death, moral weakness, and a sin propensity within original sin, Augustine was the first to add the concept of inherited guilt (reatus) from Adam whereby an infant was eternally damned at birth.

Although Augustine's anti-Pelagian defence of original sin was confirmed at numerous councils, i.e. Carthage (418), Ephesus (431), Orange (529), Trent (1546) and by popes, i.e. Pope Innocent I (401–417) and Pope Zosimus (417–418), his inherited guilt eternally damning infants was omitted by these councils and popes. Anselm of Canterbury established in his Cur Deus Homo the definition that was followed by the great 13th-century Schoolmen, namely that Original Sin is the "privation of the righteousness which every man ought to possess," thus separating it from concupiscence, with which some of Augustine's disciples had identified it, as later did Luther and Calvin. In 1567, Pope Pius V condemned the identification of Original Sin with concupiscence.