The ministry of a supreme pastor with the power of jurisdiction to maintain universal unity and orthodoxy within the Christian Church.
This, my friends, was the ministry of the fisherman named Simon Peter and that of the Roman bishops who succeeded him. And anything more than that --such as the Popes princely manner or temporal (i.e., political) authority --is not intrinsic to the Papacy as Christ created it at all. Rather, these things were added on to the Papacy via its historical experience throughout the first millennium of the Christian era, which (whether rightly or wrongly) forced the Popes to adapt their style of ministry in order to meet the challenges which presented themselves to the Church. And, by these challenges I, of course, mean things like:
The legalization of Christianity by the Roman government (c. 313 A.D.), in which the Church was transformed from a persecuted, underground society to the official religion of the Roman Empire; thus requiring the Popes to operate within the perimeters of imperial Roman law (e.g. the first Ecumenical Councils), and to deal with other secular influences creeping into the Church.
The fall of the Western Roman Empire (in 476 A.D.), in which the Papacy acquired the awesome responsibility for holding Western civilization together.
700 years of struggle (c. 342-1054 A.D.) between the Roman Papacy and the Emperors of Constantinople for control over the universal Church. In this, the Byzantine Emperors (the successors of Constantine) saw themselves as the Christ on earth, who wielded final authority over the Church (especially in the East). Thus, it was through competing with these emperors (many of whom were heretics) that the Popes of Rome were forced to acquire their emperor-like trappings. Emperor-like trappings which were equally useful in maintaining peace and relative unity among the warlike kingdoms of medieval Europe; and thus preserving Christian Europe from invasion by the Muslims.
Fiirst of all, I'm sure we can all agree that Christ desired His Church to be one --united in Faith; and that He intended His Church to remain united for all time. This is quite clear in Scripture, as when the Lord prays over the Apostles in John 17:20-21, saying: I pray not only for them, but also for those who will believe in me through their word, so that they may be one, as You, Father, are in me and I in You, that they also may be in us, that the world may believe that you sent me.
And this kind of unity continued throughout the Apostolic age:Acts 4:32: "The community of believers was of one heart and one mind ..."
1 Corinth 1:10: "I urge you, brothers, in the name of the Lord Jesus Christ, that all of you agree in what you say, and that there be no divisions among you, but that you be united in the same mind and in the same purpose."
Philippians 1:27: "...that you are standing firm in one Spirit, with one mind struggling together for the faith of the Gospel, not intimidated in any way by your opponents."
Philippians 2:2: "...complete my joy by being of the same mind, with the same love, united in heart, thinking of one thing."
Ephesians 4:1-6 -- ...bearing with one another through love, striving to preserve unity of the Spirit through the bond of peace: one Body and one Spirit, as you were also called to the one hope of your call; one Lord, one Faith, one Baptism; one God and Father of all ...
1 Peter 3:8: "Finally, all of you, be of one mind ..."
So, does this describe the state of Christianity today? Do all those who claim the name Christian share such unity with one another? Far from it. We are living in a time when there exist well over 28,000 separate Christian denominations --all with the same Bible, yet all interpreting it differently. Thus, the problem of Christian disunity has, at its core, the error of heterodoxy --the very thing condemned in the Scripture quotes above.
But what about after the Lords Ascension into Heaven? At this point, anyone and their brother could claim that they were speaking for Christ and for orthodoxy (e.g. Acts 15:1-2). Therefore, is it not reasonable to assume that Christ would appoint a vicarious shepherd --a final authority, who could settle such disputes among Christians? ...That is, someone who could stand in Christs physical place, and so continue to preserve unity and orthodoxy among the faithful. Well, thats exactly what the Scriptures present to us.
In John 21:15-19, the resurrected Christ, in the midst of the Apostles, commands Simon Peter three times to feed my lambs and tend my sheep. Now, earlier in this same Gospel (John 10:11-16), Jesus presents Himself as the Good Shepherd, and says how there is to be but one flock and one Shepherd. Therefore, the immediate question springs to mind: If Christ is the Good Shepherd, why cant He feed and tend His own sheep????
Now, clearly, Jesus can. After all, He is God. Yet, if thats the case, why is He commissioning Peter to do it? Clearly, in John 21:15-19, Christ is speaking in an earthly, vicarious sense. Notice, for example, how the sheep do not cease to belong to Jesus. They are still my sheep. Yet, Peter is told to feed and tend them. He is, therefore, being commissioned to act as Christs stand-in after the Lords Ascension into Heaven. Jesus will remain the one Shepherd, yet Peter will feed and tend the sheep, in the sense that Jesus will not be physically present to do it. Thus, Peter will be the visible, vicarious shepherd of the flock.
And we can see this quite clearly in the original Greek. For example, the word which is used for feed in John 21 is boskein --a word which the Jewish historian Philo of Alexandria, and other 1st Century writers, use to denote spiritual nourishment. Similarly, the word tend is actually the Greek poimanao --the same Greek word which is translated as rule in Matt 2:6, Rev 2:27, Rev. 12:5, and Rev. 19:15, where it is applied to Jesus Himself. Therefore, like Jesus, Peter is to rule over the sheep, and to supply them with spiritual nourishment. Thus, Peter is established as the vicarious shepherd (i.e., supreme pastor) of the Church in Christs physical absence.