A major socio-political development during the reign of Tiberius and Sejanus was the Judean governorship of Pontius Pilate, and the emergence of Jesus Christ and the Christian religion that followed. Not only would the story grow into the most overwhelming religious force in the western world, but it also provides an important indication of the independent power of Sejanus and the contrasting imperial policy of Tiberius' tenure.
While evidence of Pilate's youth and career prior to Judaea is limited, the historical record indicates that he was appointed in or around 26 AD. Named Prefect (incorrectly called Procurator by Josephus) to replace Valerius Gratus (who had been Tiberius' first appointment) Pilate was very likely named by Sejanus, and not Tiberius, to govern the Jews. At this point Tiberius had very likely already withdrawn to Capri, leaving Sejanus in virtual charge of the empire. Even had Tiberius directly appointed Pilate, its quite clear that Sejanus would've had considerable influence over the selection. This could be of significant importance to the history of early Christianity and Jesus, because Sejanus was oft-accused of anti-Semitism in the ancient sources. Of course, those sources, Josephus and Philo of Alexandria, wrote from a Jewish perspective, but they paint a vivid portrait of Sejanus position towards Jews. Pilate too falls largely under the same accusations, even though there is evidence to the contrary. Coinage issued by Pilate seems to indicate a happy tolerance of both Paganism and Judaism, but the writers tell a different tale.
Sejanus' involvement is important to Pilate's behavior in the discussion of the Jesus mystery because it helps to corroborate at least some parts of the gospels, and other historical evidence. If Sejanus had direct authority over Pilate, which he would've after 26 AD regardless of Tiberius' initial involvement, then his feelings towards the Jews would likely have become part of the imperial policy. Though the Romans were generally smart enough to attempt appeasement, Sejanus was not necessarily a man who worried about appeasing anyone. He was a manipulator whose tactics seem very similar to those of Pilate's in Judaea. According to Philo, Sejanus planned to destroy the Jews completely. It would stand to reason that his governor would follow suit. In part at least, it seemed that he did. Pilate used a methodology of baiting the people to incitement, using their own protests as an excuse to force his will, and likely that of Sejanus.
According to Josephus, Pilate's first major act was that he ordered Roman standards brought within the walls of Jerusalem (a direct violation of the sanctity of the Jewish faith honoring false gods). The Jews reacted expectedly, but on this occasion Pilate only threatened to kill them (assuredly after at least some small punitive actions had been taken), before agreeing to removing the standards. Pilate also used money from the Temple treasury to construct an aqueduct. When the Jews assembled outside his quarters to protest, this time Pilate did not relent. He ordered soldiers to dress like the Jews and mingle among the crowd. When the trap was set Pilate sprung it by signaling his men to draw clubs hidden in their clothes, beating and killing many Jews. Pilate's behavior was largely one of disdain for the people he governed, but events were about to take place which would change that entirely. Under normal circumstances, it seems that Pilate would likely have cared little about instigating violence among the people, and seemed to rather encourage it. Why then would he later give up Jesus in the famed, yet completely unrecorded events (from a Roman perspective) surrounding the trial and crucifixion of Jesus? At a minimum, Pilate's behavior clearly changed after the fall of Sejanus.
In 31 AD, after Tiberius had roused from his deference to Sejanus, and had him executed for treason, the situation all over the empire changed dramatically. Pilate had much to fear from Rome as Tiberius set about eliminating Sejanus' supporters over the next few years. In erasing the attitudes of Sejanus, Tiberius also reversed the general policy of the empire towards the Jews. While under Sejanus the Jews were poorly treated, Tiberius by contrast, and simply to counter Sejanus (as Tiberius was no lover of Judaism himself), ordered that the Jews be tolerated. This imperial policy shift probably caused a great deal of consternation for Pilate. If the gospels are to be believed Pilate was soon faced with a dilemma that would not only challenge his authority, but if not handled correctly, could cost him his life. Despite his own personal feelings towards the Jews, his fear for Roman social status and survival would dictate his behavior. Normally Pilate would've resisted any attempt by the Jewish leadership to influence him, and in fact might have openly opposed their wishes. Had the Jews been incited to violence, this could offer an opportunity to go on the offensive, shrouded in the necessity to maintain order. With Tiberius back in charge, however, Pilate, and everyone else had to tread a very fine line. The Jews, it seems, were also very much aware of this.
Sometime after 32 AD and prior to Tiberius death in 37 AD, Jesus was brought before Pilate for treason against Rome. As the story goes, which is told most importantly in the Gospel of Mark, by Josephus and also by Tacitus, the Jewish leadership wished Jesus killed essentially for being a blasphemer against their faith and against them personally. Jesus and his teachings were subversive to ancient Jewish culture, and they had to have him removed in order to preserve their tradition and authority. However, only Pilate had the authority to address the matter, and Pilate, as has been suggested, was normally in position to oppose Jewish desires at any opportunity. Pilate's attempts to free Jesus, regardless of any numerous false stories regarding divine intervention, likely only stemmed from his desire to boost anyone who opposed the Jewish leadership. Jesus was just such a man to continue stirring the Roman policy of incitement. However, what Pilate was ultimately faced with was the potential for the treason trials of Tiberius back in Rome.
Despite several attempts to resist demands of Jesus death, Caiphas and the Jewish leadership wisely invoke the use of the term 'Amicus Caesaris' against Pilate to get their way. This term 'friend of Caesar' were not just theoretic words of friendship but practically functioned as a title. Losing that title, in Pilate's case by not following Tiberius' new Jew-favorable policies, might not only cause him to lose his job as Prefect, but potentially his social standing, and at worst his life. The Jews with full knowledge of Roman politics, because of Pilate's previous behavior and relation to the known traitor Sejanus, knew exactly how to force their will. Faced with a man accused of being 'King of the Jews', a crime against Tiberius himself, Pilate had no choice but to relent, and crucified Jesus in order to preserve the peace, and his own skin.
Though the facts of the historical Jesus and the life of Pilate are debatable, it is quite clear that had Jesus lived, he would've faced crucifixion after the fall of Sejanus. By late 36 Pilate had been recalled to Rome, though perhaps fortunately for him, Tiberius died while he was en route. By that reasoning the historical Jesus must have been crucified between 32 and 36 AD. Regardless, of the 'truth' of the matter, the story of the Christ spread from this point and throughout the Roman world. Initially under the missions of men such as James and Paul, the fledgling faith spread first among the Jews than into the eastern provinces. Under Peter, Christians began to appear in Rome and within approximately 400 years, the cult that started under mysterious circumstances during the reign of Tiberius, and Sejanus, was the dominate faith of the western world. As for Pilate, after his recall from Rome, virtually no evidence exists of his fate. Stories of his conversion to Christianity, suicide out of guilt or to avoid punishment are completely unverifiable and Pilate disappears from the historical record with the passing of Tiberius.