Not long ago Adele Reinhartz wrote a brilliant piece in Marginalia entitled “The Vanishing Jew of Antiquity,” in which she addressed the current fad of translating Ioudaios by "Judean" rather than "Jew." Reinhartz's notion of "the vanishing Jew" mirrors exactly my concern about scholarly commitment to using circumlocutions like "Christ-believers" to describe what the rest of the world knows quite rightly as "early Christians." What it does is effectively rob Christians of their most defining cultural achievement, namely the New Testament, and also drives a wedge between the apostolic church and the historic Catholic and Orthodox churches. It must assume some radical shift at some ill-defined time following the apostolic period from "Christ-believer" to "Christian." When did Christ-believers stop being Christ-believers and start being Christians? Likewise, when did Judeans stop being Judeans and start being Jews? Such terms don't just rob Judaism and Christianity of their respective heritages but also fail to achieve the historical precision their proponents claim.
There are insurmountable historiographical difficulties in such procedure, which can be demonstrated via Zeno's Arrow. Christians c. 2000 are not Christians c. 1000. Yet we call both "Christians." Christians c. 1000 are not Christians c. 500. Yet we call both "Christians." Christians c. 500 are not Christians c. 250. Yet we call both "Christians." Christians c. 250 are not Christians c. 125. Yet we call both "Christians." Christians c. 125 are not Christians c. 63. Yet suddenly we need a new term for the latter. Two problems present themselves. First, what, empirically, happened between 63 and 125 to warrant this change in term? Second, is it the case, as necessarily entailed by the above, that Christians c. 125 have more in common with Christians c. 2000 than the former has with the Christ-believers of 63? Note that these problems would remain regardless of where one draws the line between Christ-believers and Christians; draw it earlier, draw it later, you will simply be substituting the numbers.
These days the standard answer to the first question is that in the late first-century the movement shifted from being a Jewish sect to a predominantly Gentile religion. We can reasonably grant that reality; whereas the entirety of the New Testament, save probably Luke-Acts, is composed by Jewish persons, from the Apostolic Fathers on almost every ecclesiastical writer of record is of Gentile descent. There was a demographic shift in the Church, no doubt. Does it follow that it ceased to be one thing and became another? Is this shift actually more profound than those wrought by the great missionary expansions of the early middle ages or the 19th-century? Today there are more Christians in the Americas than in either Africa, Asia, or Europe; the Apostles could not have conceived of such a demographic shift, not least of all because they did not know that the Americas were even a thing; if the demographic shift of the late first-century brought about a loss of identity should not this demographic shift also? In other words, why do we privilege this demographic shift as identity-destroying?
The answer is remarkably simple. The insistence on "Christ-believer" (or comparably cumbersome, needless, and unenlightening circumlocutions) is of course simply an example of the way in biblical scholarship still operates with a whole host of hidden Protestant suppositions. German Protestant scholarship of a century ago--and more recently; it's certainly present in Bultmann's work--thought of Christian development in terms of a fall from the Spirit-led Christianity of the apostolic age to a hierarchical and rigid "early Catholicism." This simply reproduced in the bluntest of terms the old Protestant saw that Catholicism was a deviation from true Christianity; it was a fall narrative, no more. This narrative was born out of debates germinated in the Reformation and Counter-Reformation: the Protestant churches, in order to sustain their claims to restore authentic Christianity had necessarily to suppose that the Catholic Church had suffered a historical fall from authenticity; the Catholic Church countered with an untenably strong form of the Vincentian axiom that the Catholic faith affirmed what had been believed everywhere, always, and by everyone. Both claims were grounded in a faulty philosophy of history, one that identified continuity with stasis, such that any change must indicate discontinuity (this of course is the fundamental problem with the Vincentian canon, but that's another matter). Under such a philosophy of history Christians of the first century cannot belong to the same religion as Christians of the twentieth, given the great changes that are manifest between the former group and the latter. Thus a different term is needed for the former. All that has differed are the terms: Christian is now the earlier rather than the later term, signifying the fall from grace (and interesting that precisely at a time that Christianity has fallen into ill-repute in many sectors of the academy NT scholars are in a rush to claim that those who wrote the New Testament were not Christians).
The difficulty with such thinking should be obvious. The first principle of history is that change is a constant. This thing called "Christianity" is historical precisely because it has been changing constantly for two millennia. If change is identical to discontinuity such that a new term is needed every time a thing changes then we should need to have a different noun for Christianity in every century, perhaps every decade or even year of its history. Except it cannot have a history, for "it" would not exist. What would exist would be a Whiteheadian series of individuals which just have the illusion of identity. Such would make the work of historical investigation impossible.
Fredric Jameson has argued that "It is safest to grasp the concept of the postmodern as an attempt to think the present historically in an age that has forgotten how to think historically in the first place." That is exactly the problem here. More specifically, the problem here is an attempt to think historically from within what Lonergan would describe as an idealist epistemology, one in which ultimately the only reality that we have consists of ideas, and in its even more banal articulation, words. It is an epistemology that cannot grasp history because it cannot grasp that there is a real world, and unable to grasp that there is a real world it cannot grasp that there was a real past world. And so all that is left is to quibble about terms, labouring under the delusion that in so doing we are generating anything even resembling light.