In John 10, Jesus proclaims "I am the good shepherd." Clearly, this image would have had immediate significance to those who lived in the agrarian society of Jesus' day. All kinds of apt comparisons can and have been made throughout Christian history between the shepherd/sheep relationship and that of Jesus and his followers. However, it is important for us to recognize that when Jesus chooses to describe himself in this way, he is not pulling just any old metaphor out of the culture that surrounds him. He is using imagery that has been central to Israel's thinking about itself, its leaders, and its relationship with Yahweh.
Of course, Psalm 23 stands out with the well known "The Lord is my shepherd"; a reminder that God is ultimately the shepherd of his people. However, shepherding imagery was also used to describe the kings and priests of Israel. These leaders were meant to be God's shepherds of his people as well. In Jeremiah 23, God says through the prophet "Woe to the shepherds who destroy and scatter the sheep of my pasture!". God promises to remove these shepherds and replace them with new ones who will care for his people. Again in Ezekiel 34, God accuses the shepherds of Israel of feeding themselves instead of feeding the sheep and of allowing the sheep to be carried off by wild beasts. Therefore, God promises to rescue his sheep from the very shepherds who are supposed to be rescuing them from these wild beasts.
Jesus' declaration "I am the good shepherd" is not only a metaphor drawn from agrarian society, nor is it only an image drawn from Israel's history. It is also said in response to the action of the Pharisees in John 9. Jesus statement in John 10 follows immediately on the heels of the story about a man who was born blind whom Jesus had healed. Throughout chapter 9, the Pharisees are trying to make sense of how it is that Jesus, whom they regard as a sinner, could possibly have healed this man's blindness. When the man who has been healed of his blindness refuses to change his story about Jesus, they cast him out of the synagogue.
It is easy for us to hear this story and regard the Pharisees and "the Jews" (John's name for those who oppose Jesus even though Jesus and all of his followers are Jewish as well) as legalistic. After all, John doesn't spare any trouble to paint them in an entirely negative light. However, we should recognize that the Pharisees are simply carrying out their role as Israel's shepherds. They didn't set out to be legalistic. (I've yet to hear anyone proclaim that as a personal life goal.) But they have heard those passage from Jeremiah and Ezekiel all their lives. As the religious leaders, the "pastors" of their day, they see themselves as the shepherds of Israel and they take that responsibility very seriously, as they should. After all, it was the shepherds of Israel whom God faulted for Israel's previous collapse when they were taken into exile. They are simply trying to avoid the mistakes of their ancestors by making sure that God's Law is lived out in Israel and that means casting false prophets (like Jesus) and their followers (like this blind man) out of their midst so that Israel may remain pure.
It is in response to these actions by the Pharisees that Jesus says "I am the good shepherd". Actually, Jesus uses two metaphors to describe himself in this chapter. He also says that he is the door or gate by which the sheep enter the fold. On one hand, we can see this as a very confusing mixture of metaphors. In one verse, Jesus is the gate and in another he is the shepherd. On the other hand, this mixture of metaphors is a very accurate theological depiction of Jesus; he is both the way into the flock and the one who leads and cares for the flock, both images are appropriate. In fact, Jesus may even be drawing on a common practice of the day in which the shepherd would lay down in the opening of the sheep pen, thereby actually serving as its gate. Either way, we have an image here of what Jesus says later in the Gospel of John: "I am the way, the truth, and the life. No one comes to the Father except through me." The purpose of this statement is not to declare one religion better than every other. Its purpose is to say that the way to God is not a religion or a morality or a belief system or a set of practices; the way to God is a person; namely Jesus Christ. The gate is the shepherd. The way is a person. The essence of the Christian faith is nothing other than knowing, following, and being in relationship with the God made flesh in Jesus Christ and having our lives transformed by that relationship. All of our doctrines and practices only serve the greater purpose of guiding us in that relationship; they are not a replacement for the relationship itself.
The Pharisees mistake isn't that they are legalistic while Jesus is lenient. It is isn't that they take sin and holiness and the Law too seriously and that God doesn't really care much about those things any more. The Pharisees mistake is their failure to recognize that the Lord who is their shepherd is standing right in front of them in the person of Jesus. The religious leaders became so accustomed to functioning as shepherds and even gatekeepers that they forgot their own role as sheep. They were so busy "caring" for the sheep that they forgot to listen for the voice of their own shepherd and they eventually became so deaf to that voice that even when he stood among them they no longer recognized him as shepherd. Jesus proclamation of himself as the good shepherd is at least in part a challenge to the Pharisees to recognize that in their attempts to be good shepherds they have failed to be good sheep.
This is the danger for many life-long Christians as well. As we grow and mature in Christ, we are rightfully expected to take on roles of leadership and discipling others. We become shepherds to others in the faith. As we spend more time and energy teaching others the beliefs and practices of the Christian faith, we become accustomed to our role as shepherd, so much so though that we forget we are also sheep. In all the shepherding of others, there is a danger that we will fail to listen for the voice of our own shepherd and so eventually become deaf to the sound of his voice.
This is part of the beauty of Psalm 23. David is the shepherd of God's people. He is the king. He has reached the pinnacle of earthly power and he knows that it is God who has put him there. He knows he has been appointed by God as shepherd and yet he still says "the Lord is my shepherd". There is a recognition that even as the ultimate earthly shepherd he is still a sheep and there is still a higher shepherd for whose voice he must listen. As followers of Jesus, we are first and foremost a people who hear and follow the voice of our shepherd.