An admirable article at Slate about the significance of Jesus' crucifixion in the first century:
A central statement in traditional Christian creeds is that Jesus was crucified "under Pontius Pilate." But the majority of Christians have only the vaguest sense what the phrase represents, and most non-Christians probably can't imagine why it's such an integral part of Christian faith. "Crucified under Pontius Pilate" provides the Jesus story with its most obvious link to larger human history.
Pilate was a historical figure, the Roman procurator of Judea; he was referred to in other sources of the time and even mentioned in an inscription found at the site of ancient Caesarea in Israel. Linking Jesus' death with Pilate represents the insistence that Jesus was a real person, not merely a figure of myth or legend. More than this, the phrase also communicates concisely some pretty important specifics of that historical event...
...It's rather clear what St. Paul meant by saying that "the preaching of the cross is foolishness" to most people of his day. As Martin Hengel showed in Crucifixion in the Ancient World and the Folly of the Message of the Cross, Roman-era writers deemed crucifixion the worst imaginable fate, a punishment of unspeakable shamefulness. Celsus, a Roman critic of Christianity, ridiculed Christians for treating as divine someone who had been crucified. A second-century anti-Christian graffito from Rome, well-known among historians who study the time period, depicts a crudely drawn crucified man with a donkey's head; under it stands a human figure, and beneath this is a derisive scrawl: "Alexamenos worships his god."
A good reminder this Good Friday.