We saw in our previous post, O is for Original Sin, that Psalm 51 is closely connected with this doctrine. In this post we find that our psalm is also intricately connected with the medieval doctrine of penance which became a formal sacramental act in the medieval period. This is a complex story and all we can hope to do is point out how Psalm 51, once again, seems to lie at the heart of matters. It is its place as the chief of the penitential psalms that is a key element of the story.
Central to early Christianity is the belief that Jesus Christ, through his crucifixion and resurrection, made a decisive end to sin. Christianity has continually both celebrated this good news and sometimes been perplexed about how this works out here and now. This is, in part, because the New Testament teaches that baptism makes an end to our sin, as we are united with Christ in both death and resurrection (see, for example, Romans 6:1–11). This is seen visually in the going down into the water, with its association with death, and of the arising from the baptismal waters of the newly cleansed baptised person to a new life. Over the centuries different responses have emerged to dealing with post-baptismal sin.
At its simplest, in the early centuries, there was an expectation of public confession during worship. Later this evolved into confession to a priest instead of gathered worshippers. Later still, as theologians continued to reflect, questions emerged over the efficacy of confession alone. Such questions became acute as purgatory emerged as a part of the anticipated afterlife. Arguably, the doctrine of purgatory was part of the same ongoing questioning and reflection.
Over time, confession became part of a bigger process, the sacrament of penance. Central to this sacrament is that a priest grants absolution of sins to the penitent and following this will allocate acts that are to be performed. These acts are a sign of the mercy and forgiveness which is the heart of the sacrament. This medieval Roman Catholic sacrament has evolved in very different ways in churches today. In some, something very close to the medieval practice is taught, in others it has been significantly reframed, and in still others, it is entirely absent.
But how does Psalm 51 fit in? The adoption of the sacrament of penance reached new heights after the Fourth Lateran Council of 1215. Among the many parts to this wide-ranging council it was decreed that adult worshippers should seek formal confession at least once a year (Canon 21). This meant, over time, that many people chose Lent as a lead up to their annual confession. This focus on a season of penitence ahead of formal penance provided a context in which the seven penitential psalms become the prayers of choice. The praying of the penitential psalms was commonly assigned as an act of penance. In this way, their chief, Psalm 51, became the keystone prayer for laity, helping it on its way to be the medieval Psalm of Psalms.