Following the teaching of the Bible, we confess that we are sinners from the very beginning of our lives. It is important to know this because it proves our deep need for a Saviour. We speak of original sin, or inherited sin, because our sinfulness can be traced back to Adam. But this raises the question: how does that work? In what way does Adam’s sin become ours?
We may distinguish between original guilt and original pollution. When Adam, the ancestor and representative of all mankind, lost his righteousness, he became guilty; and that guilt is imputed to us. This concept of original guilt was especially emphasized shortly after the Reformation, when covenant theology was developed. The Arminians challenged this: it would be unfair of God to declare guilty people who never actually sinned! The church responded in the Canons of Dort (III.3) by saying that we “are born as children of wrath”.
In practice, everyone also actually commits sins. The pollution of sin makes us “incapable of any saving good, inclined to evil, dead in sins, and slaves of sin” (Canons III.3).
It is well known that Pelagius, who lived around 400 AD, thought that this pollution was the result of children following bad examples. This view makes sin an accidental problem: it could be removed simply by setting good examples. But the church opposed this and eventually declared that Pelagius’s view is heretical. Sin has become part of our nature, as the Heidelberg Catechism clearly says in q&a 7. When we bring forth children, we automatically pass on to them an essentially polluted human identity.
An interesting question is how exactly this “sinful human nature” is passed on from parents to children. This is one of those puzzles to which we likely will never have an exact answer. In the early medieval church, the human nature was thought to be a kind of “substance”. When Adam fell, this nature became corrupted, and since our parents pass some of this substance on to us, we now have a corrupted nature as well. A modern version of this view is that since Adam’s fall, the inclination to sin is part of our DNA.
Most Reformed theologians have rejected such a “realist”, physical view of the transmission of sin. Instead, we tend to emphasize the role of Adam as covenant head. It does not answer all our curious questions, but it highlights the things that matter most: first, that we should not look for our redemption in ourselves or in other people; and second, how marvellous it is that, by faith, we may be born again “in Christ”, who takes the place of Adam but without any sin.