But Christianity has always struggled with the question of what should be done with priests it considers sinful. Once consecrated, can they be removed? Who has authority over them - secular, worldly government, or only the Church itself?

Indeed, this very argument rocked the Roman Empire during the 4th century CE.

Emperor Constantine I, having been cured of leprosy, receiving the baptism, detail from the Legend of Constantine and St Sylvester, 1246, lunette from the Chapel of St Sylvester, Church of the Four Holy Crowned Ones, Rome. Italy, 13th century. (Photo by DeAgostini/Getty Images)

With the conversion of the Emperor Constantine (306-37), Christians began to be accepted into the mainstream of Roman Mediterranean society. This was a huge change. Oftentimes marginalized, sometimes persecuted (though not as often as we might think), Christians struggled with this transition towards prominence.

And that transition wasn't smooth.

During his reign, the Roman Emperor Diocletian (284-305) required everyone in the empire to prove their loyalty to Rome by making a sacrifice. Christians viewed this as idolatry, as worshipping another god, and refused. How this was enforced varied from region to region. In and around the city of Carthage (in modern Tunisia), Christian priests were particularly targeted and forced to turn over their sacred books, which were then destroyed.

Roman Baths of Antoninus, 2nd century AD, Carthage (UNESCO World Heritage List, 1979), Tunisia. Roman, 2nd century CE. (Photo by DeAgostini/Getty Images)

Many Christians saw these tradditores ("those who handed over" - from which we get the modern word "traitors") as a betrayal, as a great sin. So, to those Christians, that sin made the priest unworthy to continue to perform his duties. The priest had to repent before he could be readmitted to the Church and even after that would be stripped of his priesthood. They were led in part by a bishop named Donatus and so were known as the Donatists.

Other Christians across North Africa thought differently. They agreed that the priests had sinned and that they needed to repent, but the sacraments those priests performed, since those acts connected this world to the divine, were always still valid. This side came to be known as the catholics (with a little "c", meaning universal).

The controversy between these groups raged across North Africa through the 4th century and often broke out into physical violence on both sides.

In the end the catholics won the argument, thanks in no small part to the intellectual support of Augustine, bishop of Hippo (d. 430).

For Augustine, the core of the problem with the Donatists' argument was the issue of the action by which someone became a priest - the ordination. Although performed by a human, it is a divine action. That matters here because it means that it can't be undone. In the eyes of the Church, a priest will always be a priest.

Saint Augustine mosaic in Cappella Palatina, Palazzo dei Normanni, Palermo, Sicily, Italy, mid 12th century. (Photo by: Mel Longhurst/VW Pics/UIG via Getty Images)

And this makes sense from Augustine's perspective as a priest and bishop himself. As such, he was primarily concerned about the path to salvation. The actions that a priest performed - the only ones in a certain sense that "mattered" - were the sacraments, the rites that connect humans to the divine, bind them to the Church, and therefore allow them to enter Heaven. If we look through that lens and that lens only, priests should be performing their sacred duties, regardless of the weight of their own sins.

Certainly, Augustine thought, all sins should be corrected and it was the Church's duty to help sinners on the path to redemption. But even in the case of murder, Augustine wrote, the sin and its correction might best be kept secret because the point wasn't punishment for breaking the law; it was again to lead the individual back towards salvation. The implication of this position should be clear. It shielded the sinner to his own benefit, even as it potentially exposed others if he continued to sin.

And we are back to Pennsylvania.

A venerable theological tradition stretching back more than 1,700 years seems to illuminate how to deal with sinful priests.

But not necessarily.

Some 400+ years after Augustine's death, another group of medieval churchmen thought it was the primary duty of priests not simply to care for their flocks' souls, but to care for their bodies as well - to protect them from violence in this world - and to act in their flock's defense. They helped spark a reform movement that changed the direction of Christian history forever.

In other words, this has never actually been a settled question. The European Middle Ages constantly debated how the Church should deal with sinful priests and others who might do harm. If understanding the past shows us possible worlds, perhaps in this one case the modern could aspire to be a bit more "medieval."