Traditional doctrine points to a sin against God, an act of disobedience, not a sin against the neighbour. And certainly, if we are to hold the doctrine of the Fall in any real sense, we must look for the great sin on a deeper and more timeless level than that of social morality.
This sin has been described by Saint Augustine as the result of Pride, of the movement whereby a creature (that is, an essentially dependent being whose principle of existence lies not in itself but in another) tries to set up on its own, to exist for itself. Such a sin requires no complex social conditions, no extended experience, no great intellectual development. From the moment a creature becomes aware of God as God and of itself as self, the terrible alternative of choosing God or self for the centre is opened to it. This sin is committed daily by young children and ignorant peasants as well as by sophisticated persons, by solitaries no less than by those who live in society: it is the fall in every individual life, and in each day of each individual life, the basic sin behind all particular sins: at this very moment you and I are either committing it, or about to commit it, or repenting it.
From The Problem of Pain
Compiled in A Year with C.S. Lewis