Tradition holds that both men were martyred in Rome during the persecutions of Emperor Nero after Rome burned: Paul beheaded, Peter crucified upside-down at his own request not to die in the manner of his lord.* Some traditions have both being put to death on the same day; others do not.
Concrete dates** are going to be hard to come by, of course, and the purported historical doings of New Testament Christians are inextricably conjoined to theological ox-goring.
But it is their lives and not their deaths that make them memorable, and to judge by the conquest of the faith they propounded, their feast day honors are richly deserved. Some scholars with no fear for their soul will tell you that Paul in particular can be rated a more consequential historical person than the Nazarene himself, having formulated the doctrine and conducted the ministry needed to turn a dead-end Jewish sect or inchoate reform movement into a surging universal religion that would play to Praetorians.
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While linked on this day, Peter and Paul appear in the Bible as sometime rivals. One might well speculate at the dynamics between them: Peter, after all, got his commission straight from the Savior himself; the upstart Saul of Tarsus, late of the Jewish establishment, arrived fired with the zeal of the converted and went from persecuting Christians to appropriating their doctrine, even calling Peter out publicly.
However they sublimated that awkwardness, their respective offices as Apostle to the Jews (Peter) and Apostle to the Gentiles (Paul) allude to an oft-explored problem whose resolution would prove decisive for the nascent faith: did Christianity require adherence to the strict Mosaic law?
The stakes: would anyone outside of already-existing Jews actually want to convert?
Paul looks like the firebrand, boldly and tirelessly enacting his revolutionary faith-alone revelation (so central to the Protestant Reformation 15 centuries later) on the pacified highways and sea lanes of the Pax Romana; Peter seems the compromiser (or a vacillator), instinctively granting precedence to the Jewish tradition but being carried along by events towards Paul.
Peter is seen in the Bible acceding to Paul’s opposition to making Greeks eat kosher and circumcise, and even persuading the most august Judaizer and leader of the Jewish Christians at Jerusalem, Saint James.
Amongst these illustrious names, we may perceive or imagine — “through a glass darkly”, as it were — what must have been a blossoming multitude of contending beliefs and practices.
Paul made Christian doctrine amenable† to the practices that would make it a phenomenal evangelical success (and separate it from the faith of Abraham), but on that same winners-write-history basis one is entitled to wonder whether the authority of Peter and James have been appropriated ex post facto by the Biblical writers of the Pauline party. If so, you wouldn’t say his reputation has suffered for it: the pope still claims to speak as “the unworthy heir of St. Peter” … and in St. Peter’s Basilica.
Whatever the faithful and the merely interested may speculate about their historicity, their names are on the founding charter of Christianity.
I have fought the good fight, I have finished the race, I have kept the faith. Now there is in store for me the crown of righteousness, which the Lord, the righteous Judge, will award to me on that day … (St. Paul, 2 Timothy 4:7-8)
A very few of the very many books about Peter and Paul and their times
* See the apocryphal Acts of Peter.
** Italian archaeologist Margherita Guarducci, however, argued that Peter’s death could be assigned to a precise date: October 13, 64. We can pose against this skepticism that Peter ever went to Rome at all, a sometime Protestant hobby-horse supposed to undermine the primacy of the Holy See.
† But not so decisively that he wasn’t soon at loggerheads with the Jerusalem Jewish Christians again.
Update: Just as this post was getting set to publish, the Vatican announced the discovery of what it claims may be the oldest image of St. Paul, a 4th century fresco uncovered in a Roman catacomb.