original sin, in Christian theology, the sin of Adam, by which all humankind fell from divine grace. Saint Augustine was the fundamental theologian in the formulation of this doctrine, which states that the essentially graceless nature of humanity requires redemption to save it. The purpose of baptism is to wash away original sin and to restore the individual to an innocent state, although even after baptism a tendency to sin remains as a result of original sin.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.