What was the biblical source of Augustine’s concept of the original sin?
St. Augustine of Hippo derives his understanding of Original Sin primarily from the Old Testament Book of Genesis. He wrote a commentary on Genesis entitled The Literal Meaning of Genesis (De Genesi ad litteram), which draws out the theological implications of the fall. In Genesis, the "original sin" was Eve and Adam eating the fruit of the tree of knowledge of good and evil, and thus becoming aware, inter alia, of sexuality, and becoming expelled from the Garden of Eden. For Augustine, the act of sexual reproduction perpetuates original sin, because we are all conceived in sin. Christ's death atoned for Original Sin, according to the New testament, and baptism would thus wash away original but not actual sin.