Caiaphas the High Priest is a harder question, with even fewer biblical mentions than Pilate. But what can we say about him?

In many ways, Caiaphas and Pilate were alike, in that Caiaphas was at least partially motivated from concern over public order. He says in Matthew, while plotting to arrest Jesus, that they must be careful when they do it, "or there may be a riot among the people." A riot would bring pressure upon Caiaphas from the Romans and threaten the power and prestige of the established religion. Public disorder threatened Caiaphas as much as Pilate. His calculation (in John 11) that one man must die to preserve the integrity of the nation was eminently practical, answering the concern that Jesus' activities would turn the Romans against the established religion. His protestations and dramatic tunic-ripping when accusing Jesus of blasphemy seem contrived, a pretense to protect the existing social order. When Caiaphas and the crowd met Pilate (in Luke 23), they charged that Jesus was "subverting our nation" and "stirring up people all over Judea" What better way to interest Pilate?

That said, what motivated Pilate, "the threat of Tiberius Caesar's displeasure?" If you mean that a rebellion or breakdown in social order would hurt his reputation in Rome and mark him as a failure as administrator, then yes. (1.) He was faced with a public riot. The Gospel of Matthew says clearly, "So when Pilate saw that he was getting nowhere, but rather that a riot was about to break out, he took water and washed his hands in the presence of the crowd, saying, I am not guilty of nor responsible for this righteous Man's blood; see to it yourselves." In the Gospel of Luke, Pilate is faced with "loud shouts" from an insistent crowd, and prudently "decided to grant their demand." In the Gospel of Mark, the "chief priests stirred up the crowd" to shout louder and louder, until finally Pilate granted their wish. Instead of Pilate believing Jesus stirred up riots (which he doesn't), we have the irony of Caiaphas and company stirring up their own riots to convince Pilate.

(2.)Pilate risked an open breach with the high priest and the entire Jewish community. All the Gospels not only place a loud and unruly crowd outside the palace, but the "chief priests, with the elders, [and] the teachers of law" escorting Jesus as well. Pilate wants to avoid the whole situation ("Take Him yourselves and judge and sentence and punish Him according to your [own] law," he says in John) but they won't let him -- they want a death sentence and only Roman authorities can do this. How will Roman authority and its relationship to Caiaphas be effected if he denies their plea?

(3.) Despite thinking the whole Jesus trial a charade built on envy, Pilate is virtually blackmailed by the Jewish leadership and crowds: "Upon this, Pilate wanted (sought, was anxious) to release Him, but the Jews kept shrieking, If you release this Man, you are no friend of Caesar! Anybody who makes himself [out to be] a king sets himself up against Caesar [is a rebel against the emperor]!" One gets the sense they were not only questioning his patriotism but threatening to inform Rome of his weakness. Crucify Jesus or we'll tell Rome you coddle anti-Roman rebels.

So, I think Stephen may have a point, in an impish, irreverent way. Caiaphas was defending an old and established religion at relative peace with Roman authority from a rising populist threat that promised to destroy both; what kind of religious and political authority will we have then? Who knows? Pilate's job was to maintain and promote the Roman Empire in Judea. With the Jesus crisis, he was faced with a Jewish riot, a possible breach between the province's established religion and Roman authority, and blackmail. What were practical men supposed to do?