“So they took branches of palm trees and went out to meet him, crying out, ‘Hosanna! Blessed is he who comes in the name of the Lord, even the King of Israel.’”
The crowds had followed him to Jerusalem. Even more crowds had come out to exalt him as king while he entered. People were no longer whispering about who this Jesus of Nazareth could be; instead, they were shouting “Hosanna!” Beckoning him to save them now. They had heard of his fame, seen his miracles, and believed that he was the rightful King of Israel. They knew, rightly, that Jesus had the power to overthrow the occupying regime and take his proper place on the throne. But they did not understand the path he must take to get there, and that his crown at the end of the week would not be one of gold but of thorns. They did not see the true enemy that must be defeated and how he would overthrow that enemy. Although he had told them, they did not realize that real power is only found in the weakness of self-sacrifice.
What They Were Thinking
In the Gospel of Mark, just verses before the triumphal entry of Jesus into Jerusalem to initiate the events of Holy Week, James and John were trying to position themselves for power in Jesus’ imminent kingdom. They had been with him for his whole ministry. They knew where he was headed and had no doubts that he was the king about which the prophets had written. However, with their worldly view of power, they wanted to set themselves apart from the rest and requested that Jesus assure them of their positions now. Instead, Jesus turns their idea of power on its head, famously telling the disciples that if they would be great, they must be the willing servants of all (Mark 10:43-45). What he communicated with words in that moment, he showed them visually in the triumphal entry, his feet dragging on the ground as he rides a colt into the city of David.
On Palm Sunday, the disciples—like many of us—saw Jesus as their ticket to power, fame, and influence. Having been oppressed in their own land their whole lives, they saw what they believed to be Jesus’ impending overthrow of the Roman Empire as their chance to wield the power to which they had always been subjected. Their vision of power was finally within their reach; but Jesus would explode their expectations—and ours as well.
Where He Was Heading
Making his way down the Mount of Olives on the back of a donkey’s colt (Luke 19:37), the disciples and the crowds would have been expecting Jesus to make his way straight to the power they were craving. The context couldn’t have been more apparent: the King of Zion comes mounted on a donkey (Zechariah 9:9), and he will fight against evil from the Mount of Olives (Zechariah 14:3-4). Jesus’ path was indeed to his throne, but it was by way of the cross. He would wield his power by laying his life down for our ransom (Mark 10:45). What James, John, and the rest of the masses didn’t see is that they all stood condemned in the evil that the king had come to conquer. Had Jesus, the sovereign king of creation, gone straight to the throne, they would have been left outside of the kingdom in the failure of the first Adam. But, as the last Adam, Jesus went to bear the curse of God and set right what we made wrong. Adorned with thorns—the sign of Adam’s fall—Jesus’ seeming defeat at the cross was the wielding of his true servant kingship and the paradoxical way he accomplished his mighty victory. 
The cross is a climactic point to which all of redemptive history had up to that point been headed. It was the plan in eternity past (Ephesians 1:3-6), declared in the garden (Genesis 3:15, 21), foreshadowed in the sacrificial system (Leviticus 16), and fulfilled in Christ (Hebrews 10:12). Jesus, the true king, had come to reign through serving. It is in God’s loving nature to offer himself sacrificially;  therefore, this is the very reason Jesus had been born: to save his people from their sins (Matthew 1:21) by dying in their place. 
Why We Are Rejoicing
Palm Sunday was Jesus’ first steps down the path of Holy Week to his terrible destination on Good Friday, where the blood of the covenant—his blood—was spilled to set the prisoners free (Zechariah 9:11). However, because we can look back and see that Good Friday was indeed good, we can also look back to Palm Sunday and rejoice with the crowds. The Son of David, the King of Israel, has come and rescued his people from the powerful sway of evil. Yet, by faith, we see rightly that we were counted in that evil. We were Christ’s enemies, but he died for his enemies to make them his friends.
God created Adam and gave him power and rule over all creation, and we praise God that in Christ—the second Adam—we see how that power is properly exercised. We rejoice because we have been made sons of the servant-King, and we live under his loving rule. Palm Sunday reminds us that the way of Jesus, and therefore the way of the Christian, is the way of a humble king, with toes dragging on the ground, coming to serve those who don’t deserve it.
  Jeremy Treat, The Crucified King, 252.
  Fleming Rutledge, The Crucifixion, 247.
  J.I. Packer, Knowing God.