The relevant scriptures are Ezekiel 34:11-16, 20-24 and Matthew 25:31-46.
I imagine that an individual's political power and his physical power were originally one and the same thing. The strongest guy in the tribe and best fighter was made chief. In return for successfully defending against the raids of rival tribes and leading raids against others he got the biggest share of the loot, the most slaves, the best food and his pick of the women. It was a trade-off the others in the tribe were willing to make in exchange for security. It wasn't a bad system if the man in power was a just and reasonable guy. But it had to be very tempting for the leader to just take whatever he wanted, even if it belonged to another member of the tribe. And if the biggest guy was a jerk or a bully, it could be quite intolerable. The only solution was for some other big guy to take him on and depose him. This was never a sure thing and the aftermath would be very bad for those who backed the losing side.
From chieftain to king to emperor, variations of the strong man rule has continued right up to this day. People want a strong leader, especially when they need protection against a nation or another group of people. Sometimes they think a strong leader can offer security against impersonal forces, like the economy or the climate. To that end they are willing to give up a lot and tolerate a lot of bad behavior on the part of their leaders.
And that happened to God's people as well. When David's kingdom split under Solomon's son, the northern kingdom of Israel and the southern kingdom of Judah suffered under kings both strong and weak, both bad and good. The result of this highly unstable leadership was that the kingdoms fell to successive empires, the northern to Assyria in 722 BC, the southern to Babylonia in 588 BC. In both cases, the empire in question would take the aristocracy and artisans of the conquered Hebrew nation into exile. The cream of the 10 tribes of the northern kingdom were so assimilated that they never returned home but were lost to history. The exiles of the southern kingdom maintained their religious identity even in Babylon, substituting a devotion to God's law for worship at their destroyed temple back in the ruins of Jerusalem. They formed communities and naturally leaders arose. And inevitably some of those leaders were abusive in the exercise of their power.
Ezekiel was a prophet ministering to a community of Jewish exiles. He proclaimed God's judgment on those leaders who enriched themselves at the expense of their followers while neglecting their needs. These false shepherds would be removed and God himself would be their shepherd. He would seek out his sheep, scattered throughout the Babylonian empire. He would return them to their home. He would give them good pasture. He would make them lie down. He will bind up the injured and strengthen the weak.
The metaphors aren't hard to decipher. The promise to bring the sheep home was a promise to end the exile of God's people. And in 70 years, that promise would be fulfilled. Cyrus the Persian would conquer Babylon and give the Jews permission to return to their homeland.
The promise of good pasture was a promise to feed the people. I'm not sure if we are speaking of literal hunger among the exiles but their spiritual hunger was obvious. "How can we sing the songs of the Lord while in a foreign land?" asks Psalm 137. Held as captives, far from everything familiar, the Jews were starving for words of comfort and encouragement. And their leaders were not providing them. God would.
The promise to make them lie down is the promise of rest. This could be rest from their wanderings. It could equally be a reference to the Sabbath, which they probably had trouble observing while living in pagan Babylon.
The promise to bind up the injured and strengthen the weak is the promise of the restoration of justice. Which also explains the line about destroying the fat and the strong. Normally a shepherd would not hurt the fat sheep and would save the most robust members of his flock. But if he had disruptive animals in his flock, here depicted as shoving and butting the other sheep out of the way so they could get the best to eat and drink, he would do something to separate them from the rest. A fat or strong sheep might be an asset but not if it is the reason the rest of the sheep are in bad shape. The needs of the whole outweigh the needs of one or two members.
All analogies break down. What God proposes would be business suicide for a real shepherd. But the people aren't animals. God cares about them. And he will not allow the strong to bully and harm the weak. With men, might makes right but God uses his might for right. Those who gets fat by hogging all the food, who get rich by rigging the game against others, who use their power to commit injustice will experience God's justice.
Note, too, that the metaphor has changed a bit. The corrupt leaders of the Jews are no longer seen as shepherds, as above the animals they take care of but are demoted, if you will, to sheep as well, albeit violently aggressive sheep whose actions divide and harm the other sheep. They must be put down, as if they were rabid.
Now this is a reversal of the way religion functions in most societies. Usually religious leaders bless the status quo. They tell the people that the strong men who lead them are put there by God. In ancient times kings and emperors were often considered divine or semi-divine. Later in European history, kings were said to rule by divine right. But here God himself is saying "No, your leaders are not doing my will. They are bad and I will depose them." Ezekiel, like prophets before and after him, fearlessly pronounced God's disapproval on certain strong leaders and the status quo. Being in charge doesn't make you special nor does it give you license to do what you wish or excuse you for breaking the laws of God. Nor may you simply disregard the "little people," or sacrifice them to your ambition. God's evaluation of who is valuable is different from that of the people in power.
This passage obviously influenced Jesus' parable in Matthew 25. He mentions a shepherd separating the sheep from the goats at the beginning of his story of the last judgment. And the criterion used is how people treated those who were weak and disadvantaged. And Jesus makes it more personal that just "this is my flock." He says how you treat the hungry, the thirsty, the foreigner, the naked, the sick and the imprisoned is how you treat him.
Why this identification with the suffering? 3 reasons. First, he is the original image of God. Just as God tells Noah that murder is wrong because human beings are made in his image, so Jesus is telling us that mistreatment and neglect of human beings is wrong because we are made in his image.
Secondly, Jesus is not only fully God but also fully human. He has undergone mistreatment. It is not theoretical to him. He knows what it is first hand and he cannot ignore it.
Thirdly, he loves us and will not let the mistreatment of those he loves get a pass.
Jesus is in fact the opposite of the strong arm leader. Jesus did not coerce people into following him. Becoming his disciple was entirely voluntary and people could and did leave him if they wished. And his kingdom would not come about like earthly kingdoms, with force. Jesus spoke of the kingdom growing organically, like a tree. It would come from within and among people who responded to his call, who recognized him as their shepherd, the good shepherd.
In Ezekiel 34, God said he would be his people's shepherd. But in the same passage, we see that God is setting up his servant David to be the one shepherd over them. Now obviously this is not the original David. Just as Israel comes to mean no longer the original man but his descendants, David comes to mean his descendant, the Messiah. Jesus, from the house of David, the great shepherd-king, is the one whom God has anointed to be prophet, priest and king over his people. He will feed the people.
On the last Sunday of Pentecost we celebrate Christ the King. Some people don't like the idea of Jesus as king because of the long history of kings abusing their power over the lives of others. But just as our sins have distorted the image of God in us, so has it distorted the image of true kingship found in Jesus. In Christ the strong and the privileged are not automatically given positions of power and leadership. In Christ leaders are not excused from obeying the laws of the land nor the law of God. In Christ you are not given power to make others serve you but power is given so you can serve others. In Christ we do not look to the powerful for examples of how to live like Jesus but to the powerless for opportunities to act like him.
The terms "nobility" and "gentleman" originally referred to aristocrats. Gradually, they came to refer instead to ideal qualities people wished their social "betters" would exhibit. Today if you call someone "noble" or a "gentleman" people think, not of their high birth, but of their high moral behavior. Just so when the Bible speaks of Jesus Christ as King, it is not describing how the rulers of this world do act but prescribing the way all people should behave. After all, we are told that in the new creation we are to reign with him. If so, we'd better start practicing, not by playing God or acting entitled, but by seeking the lost, those whom the world despises and disenfranchises. And as he stripped himself to wash the feet of his disciples, we must do likewise. Because disciples are not greater than their master. And our Master did not come to be served but to serve.