The theological idea of original sin is a nuanced one. Saint Augustine is generally viewed as the theologian who firmly established it as a doctrine in the face of challenges to the idea from Pelagius. This is not the place to rehearse this controversy. Our interest here is with Psalm 51 and how it appears to proclaim the doctrine.
In this post we will let Augustine speak for himself using quotations from his sermon on Psalm 51 (for him Psalm 50). When we allow him to speak we first find, unsurprisingly, that Augustine finds original sin presented in this psalm:
David spoke in the person of the whole human race, and had regard to the chains that bind us all. He had regard for the propagation of death and the origin of iniquity, and he said, Lo, I was conceived in iniquity. But surely David was not born of adultery? Was he not the son of Jesse, a righteous man, and his wife? How then can he say he was conceived in iniquity, unless iniquity is derived from Adam? And with iniquity, indissolubly linked, comes the chain of death. Each of us is born dragging punishment along with us, or at any rate dragging our liability to punishment. [p.418, Augustine, Psalms 33–50]
More, surprisingly as he comments further on the key verse (our verse 5, his verse 7) we find a more nuanced view of sexual intercourse that Augustine is generally given credit for:
Human beings are conceived in iniquity, and nourished on sins by their mothers while still in the womb, not because sexual intercourse between husband and wife is sinful, but because the sexual act is performed by flesh subject to punishment. The punishment due to the flesh is death. Mortality is plainly inherent in the flesh. This is why the apostle spoke of the body not as something doomed to die, but as dead already . . . [p.418, Augustine, Psalms 33–50]
Augustine’s doctrine of original sin was understood as a clarification of the theology of the nature of humanity rather than an innovation. Many earlier statements of the Fathers cohere with Augustine’s view found here in his commentary on Psalm 51, and stated more fully elsewhere in his writings. Because of Augustine’s pivotal role in defining original sin against its critics, verse 5 of Psalm 51 was read, and still is by many, as a plain statement of this doctrine. As we shall see in our next post this was not the last time that Psalm 51 would be understood as central to key doctrines in historic Christianity.
Saint Augustine, Exposition of the Psalm Volume 2: Psalms 33–50, Maria Boulding (translator), Hyde Park, New York: New City Press, 2000.