As I quite obvious from even this short list of bishops, the only sure way for the Christian to know that his doctrine was orthodox was to remain in agreement with the See of Rome. Take the years 512 to 518 as an example. Every bishopric succession except Rome had been overtaken by heresy. Why? Jesus made a promise to Peter, and he can be counted to keep it.
There are many interesting historical illustration of this protection to the Church provided by Christ through his Spirit. Once again, we must keep in mind that we are merely looking for confirmation, not proof. God has always protected the bishop of Rome from heresy, but somtimes it has been in spite of the actual man in office, and sometimes the margin of safety has been very slim. In many cases, the protection of God seems to be the only possibl explanation. For moy money, the most interesting story is that of Vigilius in the sixth century.
Theodora was the empress of the realm, ruling from Constantinople. She was a Monophysite, an adherent of a heresy that declared Jesus has only one nature, the divine. This heresy denies the human nature of Jesus, which Catholics and modern-day Evangelicals teach. Theodora determined to improse her thinking on the Pope, to bring him into line with the bishops of the East. Pope Agapitus, however, would not budge. While in Constantinople to remove a heretical Eastern bishop, he died. It seems likely that he was poisoned.
Vigilius, who very much wanted to be pope himself, was an assistant to Pope Agapitus. He met in secret with the empress and struck a deal with her. He agreed to enforce her heretical views regarding theology if she would force the Church to accept him as pope. After he was installed as pope, he would restore the bishop who had just been deposed by Pope Agapitus, even though that bishop had been dismissed as a Monophysite heretic. (It is extremely interesting that neither empress, emperor, Church, nor bishop questioned the authority of a pope to dismiss an Eastern bishop, as Agapitus had just done. They might poison the man, but they still did not dare to question the authority of the papal office.)
Before Vigilius could get back to Rome, however, Silverius was elected and installed pope after Agapitus, Silverius stood just as firm for orthodoxy as had Agapitus. He was subsequently accused (falsely) of treason and unlawfully stripped of his office by a secular general of Theodora's. Vigilius was present at the confrontation. Silverius would not resign, so he was banished to exile.
Vigilius took Silverius' place as though he were pope, although he could not be pope until the office was vacant. Vigilius was, in fact, an antipope. In spite of this, he promptly started to fulfill his promise, writing letters promoting the heresy of Monophysitism. The obvious problem he had, however, was that he could not be pope until Silverius was dead or had resigned. Vigilius seems to have made certain Pope Silverius did die, of starvation, about fifteen months after he had helped to exile him.
Reluctantly, the Church of Rome installed Vigilius as pope. To do anything else would have meant death or exile to those involved. Theodora waited for her new pope to reinstate her hertical bishop and to preach her heresy. He had done just such preaching as antipope only a few short months before. Now that he was recognized as pope, her plans could come to fruition.
But God the Holy Spirit was working a most amazing change in Vigilius. Whereas, as antipope, he had been enthusiastically defending Monophysite heresy, he now wrote the empress a letter stating that he could never teach Monophysitism or support those who did, now that he was pope. Vigilius then refused to approve a compromise solution advanced by the emperor himself. He must have known what this could mean to him. Vigilius had participated in the murder of at least one pope over just this type of refusal to compromise with heresy. His moral character had been anything but exemplary up to this point. He was guilty of both simony and murder, yet God forgave him and provided him the grace to endure his own martyrdom. While saying Mass in Rome, Vigilius was arrested by the emperor's men and deported to Constantinople. He never saw Rome again before his death, ten exceedingly difficult years later. At no point after becoming pope, however, did Vigilius teach the heresy embraced by the empress and most of the Eastern Church. Jesus had kept his promise. The gates of hell skulked away empty handed- the trophy had eluded it again. (Born Fundamental, Born Again Catholic, p. 94-96)
