- from CatholicCulture.org
Original sin refers to the state in which all humans, with the exception of Jesus and the Blessed Mother, were born. In the past, it has been described as a spot or mark on our souls that is cleansed by baptism. While there is a certain usefulness in this analogy, it falls short of a truly complete understanding of what original sin is. Essentially, as a result of Adam and Eve's initial sin and fall from grace, all humans are born into a state in which we have a tendency toward sin. This is one of the marks of what it means to be human. This tendency is referred to as original sin. When we say that baptism removes the stain of original sin, what we really mean is that, through the Sacrament of Baptism, God's grace is poured out on us and we are strengthened to resist our human tendency toward sin. Thus, at our baptisms, we are "cleansed" of that original sin and can take our place in heaven as children of God. Throughout our lives, we will continue to fall and sin, but, because of the grace we received at baptism, we can turn to God for forgiveness and mercy and He will grant it to us, in part because the penalty for the original sin committed by Adam has been paid by the "New Adam," Jesus Christ. In a way, original sin can be seen as a great gift because, without it, we would never have needed Jesus to come to earth as our savior.