One Christianity or many?

I was reading an article by Fr. R. Cantalamessa, the Pope's Household Preacher, about the figure of Jesus: "between history and.. history". He references the Pope's latest book "Jesus of Nazareth" as an original entry in the field of those who search for the historical Jesus—because it is written from 'a genuinely theological interpretation', an obvious contrast from the many secular (sociological or anthropological or historical) treatises of Jesus—clearly limited in their own methods when they explicitly discount the actions of the Holy Spirit post-Resurrection as theological—which are unable to come to a coherent conclusion about who Jesus is: "a type of first-century shaman figure; [or] a Cynic-sort of wandering wise man; [or] a visionary radical and social reformer preaching egalitarian ethics to the destitute; [or] a Galilean regionalist alienated from the elitism of Judean religious conventions (like Temple and Torah); [or] a champion of national liberation and, on the contrary, [or] its opponent and critic."

This short post isn't about the book—which I have yet to read—it's about an interesting section of the article subtitled "One Christianity or many?" The inability to scientifically pinpoint and prove beyond doubt who Jesus is, seems to find a parallel in the Christian world today: between the Catholic Church and all the other Christian 'communities', there lies a difference of opinion about what and how to teach & spread Christianity. An outsider would say that if Christians can't even agree who Jesus Christ is, it stands to believe that there can be many (forms of) 'Christianities'. Others would say that the different non-Catholic denominations grew in rebellion to the orthodoxy that Rome allegedly imposes.

I still need to come to the issue raised by those who say that in the beginning there was not one Christianity, but many, that is to say, many different interpretations of Christ's message, gradually eliminated one by one by the growing weight of the orthodoxy imposed by the church of Rome. It is possible -- why not? -- to speak of different Christianities, but then of course we need to say the same of nearly every institution and of the great novelties of history. In that sense there was not one Jewish religion but many Jewish religions, nor one Renaissance but many Renaissances, nor one French Revolution but many French Revolutions, and so on, because each of these realities were the result of the processes of the interaction and refining of various factors and tendencies. Sociologists teach us that that is what usually comes about in a movement's development from its nascent status to the establishment that is its final result.

...

The notion of an orthodoxy that emerged victorious by eliminating its competitors under the powerful guidance of Rome is a pure legend. Orthodoxy was not established in its origins by way of a movement from the centre to the periphery, but on the contrary, by movement from the periphery towards the centre. The struggles against ebionite beliefs, docetism, and encratism did not move outwards from Rome, but all arrived in Rome from Antioch in Syria, from Asia Minor, from Alexandria in Egypt, from Carthage and from Lyon in France. Rome in the first two centuries and a half of Christian history was more the arbiter between the parties than a leading force in the struggles against heresy.

Read the rest of the article, and find his logical conclusion about this attempt to separate the 'historical' Jesus and the 'theological' Jesus, and the role of the Church in this quest.