The phrase “Under Pontius Pilate” reminds us that the crucifixion of Jesus Christ was an historical event. It is an event that can be corroborated by non-gospel sources. So it is not just a story made up later by the faithful.
Monsignor Knox contrasts that when you tell a fairy tale, you open it with a phrase such as “Once Upon a Time.” But the gospel says when Pilate was procurator in Judea. And that means we can pretty much mark in history when these things happened.
And Monsignor Knox discusses why it would have been at the time of Pontius Pilate. This is a little bit of Western Civ history, so I apologize in advance. Alexander the Great was a very successful empire builder around 330 BC, and his Empire stretched from North Africa all the way to India. He spoke Greek, and so the Greek language was spread across the empire at that time. He didn’t last very long, but his empire was divided and remained established so long that the entire world came to know the Greek language in much the same way that the entire world knows the English language today.
The Roman Empire eventually followed Alexander’s and came to dominate all the way from Great Britain to Persia. The Roman civil wars ended around 30 BC, so the entire Mediterranean area was at peace. And the Temple of Jerusalem was destroyed around 70 AD. Monsignor Knox explains that that means we have about a hundred year period when the entire world understood the Greek language and the entire world was relatively peaceful and safe under the Roman Empire. This is the fullness of time when God chose to send his son to a remote corner of the Roman Empire but with a message that would change the world. And that’s why “Under Pontius Pilate” is in our Creed.