I grew up Catholic in a moderately churchgoing household and was an enthusiastic altar boy until I was sixteen. Along with my Sunday Mass duties, I showed up two or three times a week for the impossibly early, poorly attended, and much shorter daily Mass, which priests otherwise performed alone. The enjoyment I received from being an active participant in the various rituals of Catholic observance—slipping the bone-white robe over my head, cinching a red rope belt around my waist, ferrying the chalices, pouring ablutions over sacerdotal hands—was real, and I have never once looked back on those years with anything but fondness.

My loss of faith was nonetheless sudden and decisive. I will spare the reader any emotional archaeology of that event, other than to say that during my junior year of high school, while doing a report on a national newsweekly’s annual Easter-timed “Who Was Jesus?” cover story, I read a book that forced me to recognize that what I had previously accepted as an inviolate block of readily understandable scripture was the product of several cultures intergalactically different from my own. Moreover, these scriptures contained all manner of textual and translational difficulties, many of which grew more, not less, bewildering as new manuscripts and findings came historically to light. A true understanding of God via scripture suddenly seemed beyond the power of anyone I could imagine. I stopped attending Mass and soon enough abandoned Christian belief altogether. I realize that others have pondered the same quandaries and doubts and come to different conclusions; some of them have written books you will find in my bibliography. Est modus in rebus.

I have few certainties about early Christianity; I hope nothing here serves to advance fringe theories fattened by scholarly table scraps. As often as possible, I try to summarize and quantify scholarly views, though I sometimes identify those that seem to me the most reasonable. One of my goals was to try to capture something of early Christianity’s doctrinal uncertainty and how it affected the first Christian storytellers. The earliest Christian stories were about Jesus, and at least some of those telling them were presumably related to his earliest followers. Tradition has assigned a term for the most elite circle of his earliest followers: “Twelve Apostles.” Soon enough, stories were being told about them.

From 2007 to 2010, I traveled to the supposed tombs and resting places of the Twelve Apostles. In doing this, I visited nine countries (one of which I literally walked across) and more than fifty churches and spent many hours talking to the people I met at and around these sites. Most of the Twelve have more than one tomb or reliquary, but I decided early that I would limit myself, at least in narrative terms, to one site each. This book has no interest in determining which sites have the greatest claim to a given apostle’s remains. It is instead an effort to explore the legendary encrustation upon twelve lives about which little is known and even less can be historically verified.

Popular understanding holds that after Jesus’s ascension to Heaven the Twelve Apostles, working initially out of Jerusalem, quickly moved to establish identifiably Christian churches throughout the Roman world and beyond. Eusebius, one of the earliest Christian writers to attempt a proper historical account of his faith, wrote that the “chief matter” of his history was to establish the “lines of succession from the holy apostles.” But Eusebius, who lived three centuries after the apostles themselves, “failed to find any clear footprints of those who have gone this way before me.” There are few facts about the apostles in Eusebius’s pages, and as often as not they come from outside the New Testament. Indeed, since the very beginning of Christian history, the Twelve Apostles have wandered a strange gloaming between history and belief.

After the gospels, the Twelve are featured prominently within the New Testament only in the first few chapters of the Acts of the Apostles, when “divided tongues, as of fire … rested on each of them.” These divine tongues apparently grant the apostles the ability to speak in other languages. The “amazed and perplexed” people of Jerusalem wonder if these unaccountably polyglot Galileans might not be “filled with new wine,” but Peter, their spokesman, assures the crowd that the apostles are not drunk, “for it is only nine o’clock in the morning.” The Twelve Apostles go on to perform many “signs and wonders” before the people of Jerusalem. With this, save for a few brief later appearances in which they referee interfaith disputes and supply general community guidance, the Twelve as a group sink from sight within the New Testament.

How to account for the sudden disappearance of Jesus’s specially privileged followers in the only extant primary source of Christianity’s rise? The church fathers, working off a strange passage in chapter 10 of Luke, seized on talk of Seventy Disciples*—unmentioned in the other gospels—who are chosen by Jesus to spread his word “to every town and place where he himself intended to go.” Jesus even claims to have “watched Satan fall from heaven like a flash of lightning” during their travels. According to Eusebius and other church fathers, the Seventy Disciples were Christianity’s chief proselytizers.

The authors of the New Testament are not consistent in their use of the terms “disciple” and “apostle,” but in most cases they have clear differences in terms of theological responsibility. (Later use of the terms was looser. Irenaeus referred to the Seventy as apostles, and Jerome confidently bestowed the title of “apostle” upon the Jewish prophet Isaiah, who lived seven centuries before Jesus.) The term “disciple” occurs far more frequently in the gospel tradition, though it is usually unclear whether it is intended to describe followers of Jesus generally or a smaller, more privileged group within those followers. Among New Testament writers, only Paul and Luke seem to view the title “apostle” as applicable to those outside the Twelve, though Luke’s expansion of the term is fleeting. Paul had obvious self-interested reasons for seeing the title “apostle” extended to those outside the Twelve, because he himself was outside the Twelve and did not begin to follow Jesus until several years after his death.

Most of the church fathers attempted to keep the Seventy Disciples separate from the Twelve Apostles, an effort that resulted in much confusion. Clement of Alexandria, for instance, seemed to number the apostle Thaddaeus among the Seventy. He also included among them a certain Cephas. This is Peter’s special nickname in the Gospel According to John, bestowed by Jesus himself, yet Clement appeared to argue that Cephas was, in fact, a different man from Peter. Eusebius, following Clement, wrote that Cephas was “one of the seventy disciples, who happened to have the same name as Peter the Apostle.” Paul mentions Cephas several times in his letters, and while it is highly probable Paul is actually discussing Peter, it is not certain. A few hundred years after his death, even the most famous member of the Twelve had moved beyond accountable certainty.

Like the Seventy and much else that distinguished the beliefs and self-understanding of the first Christians, the notion of the Twelve is Jewish in origin and concerns one of Judaism’s first historical traumas: the capture, deportation, and “loss” of ten of Israel’s twelve tribes following the Assyrian destruction of the northern kingdom of Israel in the eighth century BCE. In his time, Jesus would not have been unique if he believed that the tribes would one day reunite in Jerusalem upon Yahweh’s final victory over the forces of unrighteousness, whereupon a new Temple would be constructed, allowing all the nations of the world to worship him. But Jesus would certainly have been unique, and radical, if he foresaw his own followers sitting “on twelve thrones, judging the twelve tribes of Israel,” as he says in the Gospel According to Matthew. This suggestion that the Twelve will in some way rule some form of a somehow reconstituted Israel is as explicit as Jesus gets in the canonical gospels about the role of the Twelve.

Most scholars believe the historical Jesus’s concerns were quite a bit more modest. They look to his stories, teachings, and parables—tales of dying beggars, angry sharecroppers, quarrelsome peasants, and hungry landowners ordering around their slaves—as indications of these more local concerns. “Jesus was not teaching some sort of new lifestyle to individuals,” the scholar Richard Horsley notes, “but addressing local communities about their disintegrating socio-economic relations.” While the precise nature of Jesus’s relationship to Judaism is a question that will never be resolved, it is difficult, nevertheless, to read the gospels without seeing the hand of the later Gentile church.

In the Gospel According to Mark, for instance, we are told that Jesus is understood to have “declared all foods clean” by instructing his disciples, “It is what comes out of a person that defiles.” We can safely assume Jesus had some basic connection to his culture and religion, which means that his tacit endorsement of shellfish, pork, and improperly butchered meat is probably not the voice of a first-century Galilean...