In Book I of St. Augustine’s Confessions he addresses the idea of original sin, that is the doctrine that man is born in sin, and is thus inherently wicked, corrupt, sinful, depraved, or various other terms that describe a similar state. In Book I, 7, 11 Augustine makes the statement that, “The only innocent feature in babies is the weakness of their frames; the minds of infants are far from innocent.” This is a key doctrine in the Christian faith
because it establishes our need for a savior, it confirms the effects of the Fall, and speaks to the inheritance of a sin nature that mankind received from Adam; Paul speaks of this in Romans 5:
“Death in Adam, Life in Christ  Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned,” (Romans 5:12 ESV).
Augustine goes on to point out the fact that man at no point in his life possesses any portion of righteousness, and that all men are guilty in God’s sight. He states, “no one is free from sin in your [God] sight, not even the infant whose span of earthly life is but a single day.” This parallels Psalms 58:3, and Psalms 51:5 both of which speak of man’s inherent sin nature even from the point of conception.
I think the most important implication of original sin is that it points to our need for a savior, for if we are not inherently wicked and corrupt, then it would mean that we could possibly achieve righteousness on our own. Indeed this is what Muslims and many eastern religions believe, and the Manicheans, whom Augustine was involved with before his conversion, also denied the inherent evil nature of man; instead they attributed it to some malevolent force that acted upon men and caused them to do wrong.
When we decide that we are, or can become, righteous in and of ourselves we quickly lose the need for a righteous Savior to atone for our sins, and justify us before a pure and holy God. St. Augustine recognized this and it caused him to worship God even more as he proclaimed, “Your will is that I should praise you, O Lord my God, who gave life and a body to that infant…” We too should praise the God who, even though we were wicked from birth, chose to extend us grace through salvation.
 All quotes, unless noted, are taken from: Maria Boulding, trans., The Works of Saint Augustine: A Translation for the 21st Century; The Confessions, ed. John E. Rotelle (New York: New City Press, 1997)