Was Peter a pope?
Question: Jesus installed Peter as the chief steward or prime minister under the King of kings by giving him the keys to the kingdom. As can be seen from Isaiah 22:22, kings appointed a chief steward to serve under them in a position of great authority to rule over the inhabitants of the kingdom. Jesus quotes almost verbatim from this passage in Isaiah, and so it is clear what he has in mind. Christ appointed Peter to lead them and guide the flock (John 21:15-17).
Answer: Christ gave Peter authority in the church and he was certainly a prominent leader. Peter is consistently mentioned first in the list of the apostles; he is often their spokesman; and he had the privilege of first preaching the Gospel to the Jews at Pentecost and then to the Gentiles at Cornelius' house.
Peter was prominent, yet that is not sufficient to prove that he was pope. The bishop of New York is more prominent than the bishop of Malta, yet the former does not exercise authority over the latter. Prominence is different from primacy and predominance.
To prove the papacy, you must show that Peter was the head of the apostles and that he exercised full, immediate and universal power in the Church. For that is exactly what is claimed by Rome:
"The office uniquely committed by the Lord to Peter, the first of the Apostles, and to be transmitted to his successors, abides in the Bishop of the Church of Rome. He is the head of the College of Bishops, the Vicar of Christ, and the Pastor of the universal Church here on earth. Consequently, by virtue of his office, he has supreme, full, immediate and universal ordinary power in the Church, and he can always freely exercise this power" (The canon law, 331).
It is evident that Christ gave authority to the apostle Peter. "And I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven" (Matthew 16:19). The issue is whether this authority was unique to Peter. Evidently it was not, for soon afterwards Jesus gives exactly the same authority to all the apostles, "Assuredly, I say to you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven" (Matthew 18:18). Hence Peter had an authority similar to the other apostles, and not an authority over them.
The apostles did not understand Jesus' words in Matthew 16 as Roman Catholics interpret them. If He made him 'chief steward' and 'prime minister' and 'the head of the college of bishops', why is it that even up to the day before Christ suffered, they were still arguing among themselves who should be considered the greatest? (Luke 22:24-26). Jesus' reply is very significant. He did not remind them what He told Peter at Caesarea Philippi, but simply scolded them for their pagan-like reasoning. "The kings of the Gentiles exercise lordship over them...but not so among you." Peter knew nothing of the "supreme, full, immediate and universal ordinary power" over the other apostles and the church. Ironically, later on in history, the bishops of Rome - who were supposedly the successors of Peter - strove and fought to gain lordship over the universal church.
Again, it is true that Jesus commissioned Peter to feed the sheep (John 21:15-17). However, this was not a unique office committed to Peter alone. The apostle Paul tells the elders of Ephesus, "Therefore take heed to yourselves and to all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood" (Acts 20:28). The apostle Peter himself says, "The elders who are among you I exhort, I who am a fellow elder and a witness of the sufferings of Christ, and also a partaker of the glory that will be revealed: shepherd the flock of God which is among you, serving as overseers, not by compulsion but willingly, not for dishonest gain but eagerly; nor as being lords over those entrusted to you, but being examples to the flock; and when the Chief Shepherd appears, you will receive the crown of glory that does not fade away." (1 Peter 5:1-4). The elders are called to feed the sheep too.
You refer to Isaiah 22:22. "The key of the house of David I will lay on his shoulder; so he shall open, and no one shall shut; and he shall shut, and no one shall open." As a matter of fact this verse is quoted "almost verbatim" in the New Testament, specifically in Revelation 3:7 and not in Matthew 16. "These things says He who is holy, He who is true, He who has the key of David, He who opens and no one shuts, and shuts and no one opens" The key of the house of David is in the hand of Christ, not Peter!
Rome would make Peter the chief shepherd, "the Church's supreme pastor (shepherd)" (Catechism, para. 857). Peter himself would never accept this usurped title for it belongs to Another. Peter calls Jesus Christ "the Chief Shepherd" (1 Peter 5:4).