The image of the Good Shepherd seen in the Gospel reading is a powerful image of Jesus’ role. This powerful image is so abundant in the Old Testament that this short article cannot begin to recount all the references. Suffice it to say that the Hebrews were a nomadic-shepherd people, and the images of the lamb and the shepherd are woven in and through their story at every glance. From the beginning God himself is seen to be the shepherd of his people.
In Genesis 48 the old man Jacob, before blessing his sons, says that the Lord God of his fathers has been his shepherd his whole life long. The prophet Micah sees the people of Israel as "sheep without a shepherd," and the shepherd King David calls the Lord his shepherd (Ps 23 et al). The prophet Isaiah says that the sovereign Lord will "tend his flock like a shepherd: He gathers the lambs in his arms, and carries them close to his heart; he gently leads those that have young" (Is 40:11).
The theme of the Lord being the Good Shepherd reaches its Old Testament climax in the Book of Ezekiel. Earlier, Jeremiah the prophet had raged against the corrupt leadership of the people of Israel. They were wicked and abusive shepherds, but in the Book of Ezekiel God himself promises to be the shepherd of his people Israel.
So the Lord says,
As a shepherd looks after his scattered flock when he is with them, so will I look after my sheep. I will rescue them from all the places where they were scattered on a day of clouds and darkness . . . I will search for the lost and bring back the strays. I will bind up the injured and strengthen the weak, but the sleek and the strong I will destroy. I will shepherd the flock with justice. (Ez 34:12,16)
Finally, the Lord’s servant, the Son of David, will come and be the shepherd of the lost flock.
I will save my flock, and they will no longer be plundered. I will judge between one sheep and another. I will place over them one shepherd, my servant David, and he will tend them; he will tend them and be their shepherd. I the Lord will be their God, and my servant David will be prince among them. (Ez 34:22-24)
One of the clearest signs, therefore, of Christ’s self-knowledge as the Son of God is when he calls himself the Good Shepherd. In story after story Jesus uses the image of the Good Shepherd to refer to his own ministry. He explicitly calls himself the Good Shepherd (Jn 10:11,14) who has come to the lost sheep of the house of Israel (Mt 15:24). He tells the story of the lost sheep, placing himself in the story as the divine Shepherd who fulfills Ezekiel’s prophecy (Lk 15). The author of the Letter to the Hebrews calls Christ the Great Shepherd of the Sheep (Heb 13:20). Peter calls Jesus the Shepherd and overseer of souls (1 Pt 2:25), and in the Book of Revelation, the Lamb on the throne is also the Shepherd of the lost souls (Rv 7:17).
When Jesus Christ, after his Resurrection, then solemnly instructs Peter to "feed my lambs, watch over my sheep, feed my sheep" (Jn 21:15-17), the ramifications are enormous. Throughout the Old Testament, God himself is understood to be the Good Shepherd. He promises to come and be the shepherd of his people through his servant David. When Jesus Christ, the Son of David, fulfills this prophecy, God’s promise is kept. Then before Jesus returns to heaven, he commands Peter to take charge of his pastoral ministry. Now Peter will undertake the role of Good Shepherd in Christ’s place.
The term ‘vicar’ derives from the fact that the vicar is a priest appointed to do a job in the stead of the official parish priest. One priest might oversee various parishes, and so he appoints vicars to do the job when he can’t be there.
Many non-Catholic Christians object to the pope being called the Vicar of Christ. But the word vicar simply stands for one who vicariously stands in for another person. A vicar is someone to whom a job is delegated. The three strands of biblical imagery—rock, steward, and shepherd—show in three different ways that Jesus intended Peter to exercise his ministry and authority here on earth—in other words, to act as his vicar.
The fact that there are three images is important because the authors of Scripture believed the number three to be one of the perfect numbers. A statement was most authoritative when it was expressed three times in three different ways.
We see this in the passage in John 21. Jesus gives his pastoral authority to Peter with three solemn commands: "Feed my lambs, take care of my sheep, feed my sheep." Here Jesus delegates his authority three times in three different ways, using imagery found throughout the Old Testament. In so doing he clearly reveals his delegation of authority to Peter.
History shows that from the earliest days Christians considered Peter to be the very rock, steward, and shepherd that Jesus proclaimed him to be. Furthermore, from the earliest days they considered his successor to be the Bishop of Rome, and that Bishop of Rome endures today as rock, steward, and shepherd—just a few hundred yards from the site of Peter’s death and burial.