UPON THIS ROCK

The Life of St. Peter

By Walter F. Murphy

Macmillan. 538 pp. $19.95

A decade ago Walter F. Murphy, a professor of political science at Princeton, took some time off to visit Rome. A distinguished student of jurisprudence, organization and administration, Murphy thought he might be able to write a scholarly study of the Vatican administration. The task turned out to be impossible, so Murphy decided to try fiction to capture the complexities of the world's oldest bureaucracy. He missed a lot of the nuances of the way the Vatican works (or doesn't work) but his "Vicar of Christ" was a superb story and became an enormously successful best seller.

Now Murphy turns on his time machine and goes back to the beginning, to the life of the man Catholics believe to be the first predecessor of John Paul II -- Peter the Fisherman. He is not the first to plow this field; his most famous predecessors have been the American Protestant Lloyd Douglas ("The Robe") and the Polish Catholic Henryk Sienkiewicz ("Quo Vadis"). As with the latter, Murphy's denouement comes when Peter runs away from Rome to escape crucifixion and then, confronted by the Master, returns.

Murphy's story does not have the compelling characterizations of "The Robe" or the literary panache of "Quo Vadis" (whose author won the Nobel Prize in 1905). However, he demands attention because of the vigorous, compelling and eminently plausible way in which he captures the organizational crises of the early church -- a strength one would expect from a professor of political science.

The story is told by a Greek named Quintus, something of a philosopher who half believes in Jesus and who both admires and understands the blustering, charismatic but weak Peter.

Quintus is presented as the first to write down the stories told about Jesus and admits that he is known to the community as "Q." That is a nice sleight of hand by Murphy, since one of the postulated sources for Matthew's and Luke's Gospels (in addition to Mark's Gospel) is a collection of sayings called "Q" (from the German word Quelle, or source).

Quintus and Murphy stick pretty close to the New Testament data: The Jesus movement was initially pluralistic, hesitant, disorganized. Was the Master to return sooner or later? Were they a Jewish movement or something brand new? Could gentiles be admitted? If they were admitted, was it necessary for them to obey the full law of Moses?

Murphy makes these formative conflicts of the early Christian movement come alive. The reader begins to understand that they were really important arguments in those days and that our world was shaped by the solutions that Peter the Fisherman reached.

Even when the story departs from the New Testament outline -- marital infidelity by Peter, a power struggle between Peter and Mary Magdalene -- the departures seem not unreasonable. Murphy has recreated with narrative skill and impressive plausibility the time when the early Christians (not even sure they wanted the name) were moving the first inches toward becoming an institution, a path down which every movement must move if it is to survive.

The figure of the Master, usually unseen as in "The Robe," hovers above the story, affecting everyone from Peter the Fisherman to, at the end, even Quintus the philosopher.

One suspects a subtext to the story: Murphy is inviting a comparison between the human frailty and moral greatness of Peter on the one hand and the pomp and corruption (as in the Vatican Bank scandals) of the present Roman Curia. He seems even to be suggesting by implication the possibility that Peter the Fisherman might have had a greater impact, precisely because of the blend of weakness and strength in his character, than did his current successor, for example, during his recent trip to America.

Walter Murphy may be telling us that precisely because of the pretense that the papacy is not human and hence not capable of mistakes, it is a long way from the Rome of Peter I to the Rome of John Paul II and that much of that way is downhill.

The reviewer, a Catholic priest and professor of sociology at the University of Arizona, is the author of "Rite of Spring."