When preachers compare the response of the crowd on Palm Sunday (“Hosanna!”, Mk 11.9; Mt 21:9) to that of the crowd just a few days’ later (“Crucify him!”, Mk 15:13; Lk 23:21; Jn 19:15) they often explain this in terms of fickleness (“How quickly they changes their minds about Jesus!”). I’ve done it myself.
But it’s not at all clear that the crowd who acclaimed Jesus’ triumphal entry into Jerusalem was the same group of people who called for his execution. The former were probably mainly pilgrims from Galilee, along with Jesus’ followers. The latter were mostly from Jerusalem itself.
In any case, the responses of both crowds was based on misunderstandings of Jesus’ mission. The crowd shouting “Hosanna!” were motivated by nationalistic fervour, whereas the people calling for Jesus’ death had been incited by those who were falsely accusing him of blasphemy.
Their common bond was not fickleness, but misunderstanding.
Based on this article by Andreas J. Köstenberger and Justin Taylor.