In the simplest, if also the least useful, of definitions, Christianity is what people who call themselves Christians believe and how they act in accord with those beliefs. Today the beliefs held by Christians are so many and so diverse, and so too the acts performed in their name, that a descriptive approach to Christianity would doubtless provide a great deal of data but would not net much understanding. As Aristotle remarked in one of his apparently off-hand statements that turn out the next morning to be one of the cornerstones of the Western intellectual tradition, “Science is about the general.” So to generalize on the matter, almost every Christian thinks that what he or she believes represents, in some degree, an original “something” that is identified as “Christianity,” and further, that Christianity, however it is defined or understood, derives from the teachings of Jesus Christ.
Jesus is long gone, of course –it is fairly certain that he was executed by the Romans in occupied Judea sometime around 30 A.D.—and so what Christians believe and attempt to follow are the reported teachings of Jesus of Nazareth. The distinction does not much bother Christians since they also believe, and have collected evidence to support their belief, that those teachings, as well as the events of Jesus’ life, are accurately recorded in the four New Testament Gospels. But though the Gospels may be an accurate account of what Jesus did, said and claimed during his brief public career, they are not yet Christianity. The New Testament, which is Christianity’s founding archive, includes a number of other writings: a dense body of Jesus interpretation in the form of occasional letters written to Christian congregations by the missionary Paul, one of the earliest converts to the new faith; a brief history of the earliest days of the Jesus movement that is called, somewhat misleadingly, “The Acts of the Apostles,” this from Paul’s follower Luke, who also wrote one of the Gospels. There are a number of other interpretive letters in the New Testament written by men identified as Jesus’ followers and even members of his family. And the collection ends with an imaginative vision of the End Time called “The Unveiling” (apocalypsis) by a mysterious “John the Elder.”
The collection, which is called the “New Testament” or “New Covenant” to set it pointedly over against the Jewish Bible or the “Old Testament,” is not the creation of Jesus nor of his immediate followers but the product of Christians of the second and third centuries from existing texts. There were debates about what should be included in the collection and what should not that lasted until the matter was settled and the canon fixed in the early fourth century. Thenceforward the New Testament has remained the benchmark and, in a sense, what we have been looking for, a definition of Christianity.
But if the contents of the New Testament provide a rough working definition of Christianity, it is also a very incomplete one. In the sixteenth century a grievous schism rent Christendom (the incarnation, so to speak, of Christianity) over the issue of, among other things, whether Christianity should be defined solely by the content of New Testament –Sola Scriptura! was the slogan of the Reformers—or whether it included, on an equal footing, a notion shorthanded as “tradition.” Tradition was generally understood, and defended as the teaching of the Church, an institution whose origins were described in the Acts of the Apostles and which had been in continuous existence thereafter. Somewhat more literally, the New Testament represented the authoritative “handing down” of the (expanded and interpreted) teachings of Jesus and his Apostles.
The schism was never settled, but what all sides could agree on was that the original teachings of Jesus and their extension by his Apostles, who provided Jesus’ words and deeds with an explanatory theological context, was handed down intact to the post-Apostolic Fathers like Augustine in the West and Basil, the two Gregorys and Chrysostom in the East, and that they were, generally speaking, authoritative and binding for Christians. The doctrinal decrees of the Ecumenical Councils, the bishops of the entire Church in plenary session (or at least the first seven of them, from I Nicaea in 325 to II Nicea in 787 A.D.) fell into the same category of authoritative and binding components of Christian doctrine.
But not for everyone. Though Luke emphasizes the unity of thought in the Apostolic generation, it is apparent from even a casual reading of Acts that the unity was never quite as perfect as Luke would have it. At the very heart of the Christian enterprise, Paul had what appears to be a rather ugly disagreement with Peter (Galatians 2:11-14) and another falling-out with Barnabas (Acts 15: 30), though this seems to have been over personnel rather than doctrine. Others differed from the Apostles on the limits of Christian doctrine, like the notorious Simon Magus is Samaria (Acts 8:9-24) and a number of unnamed parties in Corinth (1 Corinthians 1:10-11). Dissent does not shrink in the passage of Christianity past the Apostolic age. Second century Christian writings reveal a growing number of dissenters as well as a willingness to discuss them. Discussion, is however the wrong word. Dissent is rarely discussed; it is invariably attacked. Christians, some of them at least, adopted a “live and let live” attitude to doctrinal dissent only very late in the game, in the seventeenth century when it was the price they were willing to pay for political and military peace in Europe.
Christianity, then, would appear, in the aftermath of the Reformation arguments, to be comprised of 1) the Jesus testimony, his own teaching in his own words, 2) as recorded in the Gospels, and 3) as authoritatively interpreted by the early Christian “Fathers, a line that begins with Paul and either ends somewhere in the past (the Reform) or continues, through a succession of bishops, down to the present day in the (Roman) Church. The issue here, however, is not about what Jesus actually taught since we come upon that only in the four literary biographies called Gospels; it is, rather, how and why the authors of those Gospels composed their works and how and why the early “Fathers,” some of whom had access to both the written Gospels and contemporary oral tradition about Jesus, came to their interpretation of the Jesus words, acts and claims.
Questions about the accuracy and reliability of the Gospels and the legitimacy of the early Christian understanding of Jesus are answered for most Christians by the assurance, from the New Testament and the Fathers themselves, that the evangelists were guided in their work by the Holy Spirit and so are “true” in the profoundest sense of that word. And the same holds, to a certain degree, for the pronouncements of Jesus’ early followers, certainly those included in the New Testament, like Peter, Paul, James and Jude, as well as those that followed, like the two Clements, Justin, Ignatius and others down to at least Irenaeus in the second century, and perhaps Origen and Tertullian in the third, and even Augustine in the fourth, though the Patristic road gets less well lit and less certain in its trajectory as the Christian proceeds down it.
But if that explanation of a divinely bestowed and guaranteed inerrancy is denied, or at least questioned, and the counter position is stated as axiomatic, namely, that the Gospels are documents and that their authors and those who followed them were human agents whose works must be judged by available historiographical criteria, then the answer to the question “What is Christianity?” turns out to be somewhat different from what is generally assumed.
Christianity is both a movement and an institutionalized system of belief and practice, but it is also a construct or, more plainly, a “made thing” whose major components, the four Gospels in the first instance, as well as the canonical and fixed New Testament, were produced by followers of Jesus of Nazareth in the first couple of centuries after his death. It was they who composed, edited and organized the body of literature that embodies and preserves what Christians call the “deposit of faith.” This is not to say that those same Christians “invented” Christianity or that there was bad faith, malevolent conspiracy or mass delusion in the making; nor does it say that Christianity is for that reason true or false. What it does suggest, however, is that the Christians’ own story of its origins and growth, their “foundation myth,” is not the whole story.
[Note: This is the preface to an unfinished longer piece where I attempt to lay out the “whole story” of the last sentence (as if that were possible!) in more detail.]