Two popes and idolatry

How bad can a bad pope get?  Pretty bad.  Here are two further examples from history.  Marcellinus was pope from c. 296 – 304.  During his pontificate, Emperor Diocletian initiated a persecution of the Christians, requiring the surrender of sacred texts and the offering of incense to the Roman gods.  Marcellinus and some of his clergy apparently complied, though Marcellinus is also said to have repented of this after a few days and to have suffered martyrdom as a result.  Some claim that by virtue of his compliance he was guilty of a formal apostasy that resulted in loss of the papal office, though his purported repentance and martyrdom also led to his veneration and recognition as a saint. But exactly what happened is controversial among historians.  St. Augustine denied that Marcellinus was really guilty of the sins in question.  On the other hand, other ancient sources claim that he was, and the later pope Damasus I omitted reference to Marcellinus when paying tribute to his predecessors.  Nor is it clear whether Marcellinus really did either suffer martyrdom or lose his office.
However, that Marcellinus could have been guilty of these sins has not been denied by orthodox Catholic theologians, because it is not ruled out by the conditions under which a pope teaches infallibly.  Indeed, in Book 4, Chapter VIII of On the Roman Pontiff, St. Robert Bellarmine judges that it is “certain” that Marcellinus “sacrificed to idols.”  He also thinks that Marcellinus did not ipso facto lose the papal office, because he acted out of fear.
John XII, who was pope from 955 – 964, was one of the most debauched men ever to sit on the throne of Peter.  He is said to have confiscated the offerings left at the altar for his personal use, to have violated female pilgrims to Rome and effectively to have turned the Lateran palace into a brothel, and to have died while in bed with another man’s wife – on one account as a result of a stroke, and on another at the hands of the cuckold who caught him in the act.  John was also said to have invoked the names of the pagan gods while gambling. 
John brought the office of the papacy into widespread disrepute, and the period was marked by bitter factional conflict.  He was deposed by a synod in Rome, in part on grounds of “sacrilege,” and replaced by Pope Leo VIII – though the legitimacy of this series of events was widely challenged, given papal primacy, and in any event John was able by threat of force to reverse this state of affairs and get himself reinstalled as pope and Leo excommunicated.  Those who had accused John were punished by scourging or bodily mutilation.  After John’s death, Leo was restored as pope – though only after another claimant to the papal office, Benedict V, was first elected and then deposed.  (At Benedict’s deposition – to which he apparently acquiesced – he was stripped of his papal regalia and his staff was broken over his head by Leo as Benedict lay prostrate.  They played for keeps in those days.)
These examples illustrate several important points.  First, popes can, consistent with the doctrine of papal infallibility, be guilty even of sins as grave as idolatry.  Second, when their sins touch on theological matters, as they do in these examples (and as they did in a very different way in the case of Pope Vigilius), Catholics have sometimes understandably been moved to question their legitimacy.  This is theologically problematic, and in my view it cannot plausibly be maintained that Marcellinus, Vigilius, or John XII lost the papal office.  However, whatever canonical chaos temporarily afflicted the Church during the times of these popes was ultimately their fault.  Certainly one can lay heavy blame on the churchmen who tried to depose John XII, and on the emperor Otto I, who played a major role in the events in question.  But the fact remains that it is John’s extremely scandalous behavior that prompted this overreaction.  It is the pope himself who is manifestly the villain of the story.
A further lesson, however, is that these incidents are also noteworthy precisely for their rare and fleeting character.  The theological and/or canonical chaos that bad popes like Vigilius, Honorius, Stephen VI, John XII, et al. inflict on the Church can be intense but it is also always temporary, and the Church eventually so thoroughly returns to order that the chaos is soon forgotten by all but historians and anti-Catholic propagandists scrambling to find evidence that the Church succumbed to error.  The Church can get very sick indeed for relatively short periods of time, but she also always gets better.  Naïve and sycophantic papal apologists refuse to see the first fact, and the anti-Catholic propagandists refuse to see the second. 
Further reading:
The strange case of Pope Vigilius
Popes, heresy, and papal heresy
Some comments on the open letter
The Church permits criticism of popes under certain circumstances
Papal fallibility
Why Archbishop Viganò is almost certainly telling the truth
Denial flows into the Tiber