Simon Peter

Peter is the best-attested of the twelve, and the one whose later significance rests most heavily on a single sentence.

All four Gospels place him first among the disciples, give him the name change from Simon to Kephas, Aramaic for rock, rendered into Greek as Petros, and record his denial of Jesus during the trial, three times, before a cock crowed. The denial is in all four, which is a strong indicator: it is not the sort of detail a movement invents about its senior figure. Paul independently confirms his standing, calling him Kephas and describing a public argument with him at Antioch over whether Gentile converts had to keep Jewish food law. That letter is the earliest surviving Christian document mentioning him and it shows him losing an argument, which is again not an invented detail.

The sentence everything else hangs on is Matthew 16:18, where Jesus tells him that on this rock the church will be built and gives him the keys of the kingdom. The Roman Catholic reading takes the rock to be Peter himself and the keys to be a transferable office, inherited by the bishops of Rome. Orthodox and Protestant readings variously take the rock to be Peter's confession of faith rather than his person, or accept a personal primacy of honour without an inheritable jurisdiction. The Greek plays on the pun, Petros, petra, and the pun works better in Aramaic, where both words are kephas, which is itself an argument that the saying is early.

What the New Testament does not say is that Peter went to Rome, led its church, or died there. That belongs to tradition.

The Roman tradition is early but it is tradition, and its parts do not all stand equally.

That Peter died a martyr is attested indirectly within the New Testament, in the closing chapter of John, where Jesus tells him he will stretch out his hands and be carried where he does not wish to go, and the text glosses this as indicating the death by which he would glorify God. That is written from the far side of the event. Clement of Rome, writing near the end of the first century, refers to Peter's suffering and death without saying where. Ignatius of Antioch, early in the second century, writes to the Romans in terms that assume Peter and Paul had authority there. By the later second century the association with Rome is firm, and a Roman presbyter named Gaius points visitors to memorials of the two apostles on the Vatican hill and on the Ostian road.

The inverted crucifixion is later and thinner. It appears in the Acts of Peter, an apocryphal romance of the later second century, where Peter asks to be crucified head downward because he is unworthy to die as his master did. Nothing earlier reports it. It is a good story with a clear theological motive and no independent corroboration, and it should be described as what it is.

The bones are a separate question. Excavations under St Peter's from 1939 uncovered a first-century necropolis and a second-century monument, and a set of bones from a niche near it was declared by Paul VI in 1968 to be identified in a manner the church considers convincing. The archaeology of the cemetery and the shrine is solid; the identification of the individual remains is not, and the archaeologist who led the dig disputed it.