Original Sin, in Christianity, is an affirmed doctrine that is oftentimes misconstrued by those who know little of church tradition and by those critics of Christianity who are equally illiterate and unread about Christianity. Original Sin is a term that many who have grown up in a Christian culture will have heard of. But what is it?
While one of the central doctrines of Christianity and associated with the Fall—which is understood as man’s attempt to decide for himself what is good and evil for his own happiness (see, in particular, Augustine, City of God, 11.4 for an explanation of this view)—Original Sin is actually a simple doctrine that corresponds with Christian anthropology. Christian anthropology asserts two basic contentions. First, man—as imago Dei—is endowed with reason (his immoral soul) to know the good and true and be able to live by the standards of nature to consummate felicity; second, man—having fallen by sin—is irrational and is prone to irrational action.
Some might say that Christianity wants to have its cake and eat it too. On one hand Christianity affirms the specialness of man. In comparison to animals man is the only creature with the capacity to know the good and true and choose (for himself, via free will) to live in conformity with the good and true that will bring about his happiness (and therefore salvation). On the other hand Christianity sees in man a terrible tendency toward the irrational, to engage in violence, to do wrong and to rationalize wrong. Original Sin is the doctrine that codifies man’s irrational nature while the doctrine of imago Dei is that which codifies man’s rational nature and that there is an inherent tension (or dialectic) between man’s rational side and his irrational (e.g. “sinful”) side.
Original Sin is also the doctrine which affirms that all humans have this inborn tendency to commit evil, rationalize wrong, and reject the good for lower things in life which do produce temporary happiness for the self but does not produce everlasting contentment for the self and often comes at the harm of others. In other words, Original Sin is the teaching about man’s irrational tendencies and why man, in particular (given his gift of rationality) abandons rationality in favor of irrationality. Since man is a relational animal in Christianity having intimate, relational, and social lives is also important to man’s happiness and salvation. Man and woman are made for each other and complete each other in Christian anthropology.
In being tied to the doctrine of the Fall, which, again, is man’s rebellion to be the center of all decision-making as to what is right and wrong for the purpose of (deceiving oneself) deciding what will bring about one’s happiness, Original Sin is the concrete and empirical observationism about man’s darker side, immoral side, and malevolent side. It is, in a nutshell, the Christian teaching that explains why man has such a profound propensity for evil. More importantly, Original Sin entails that all men have this corrupt tendency to irrationality. Since rationality is what saves man, and Christ is the Logos (Reason) in traditional Christian Trinitarian theology, it takes the reorientation of man away from the irrational (sin) to the rational (truth) to bring about the happiness that he seeks which Original Sin taints.