Impenetrability of conscience

The action of the Spirit of Truth, which works toward salvific "convincing concerning sin," encounters in a person in this condition an interior resistance, as it were an impenetrability of conscience, a state of mind which could be described as fixed by reason of a free choice. This is what Sacred Scripture usually calls "hardness of heart." In our own time this attitude of mind and heart is perhaps reflected in the loss of the sense of sin. (Papal Encyclical, Dominum et Vivificantem, 18 May 1986).