The contrast between 'Jew' and 'Greek' can denote the linguistic divide between the Hebrew and Greek tongues, with 'Greek' also serving as a metonymy for the entire cultural and cultic difference between those whose world-view is circumscribed by the polytheistic pantheon of Greek religion and literature. The earliest and most important sources for Gentile Christianity are the seven authentic letters written by Paul c. 50-60 to assemblies of Christians. In recounting the geographical spread of the Pauline mission to the Gentiles, follow the terms of Roman provincial organisation and urban place names which Paul himself chose to employ in his letters. From Macedonia Paul and co-workers Timothy and Silvanus moved into mainland Greece. Early catholicism is sometimes used to refer to the developments in Gentile, particularly Pauline, Christian communities in the third generation, as they are known to everyone in the Pastoral Epistles, the letters of Ignatius and Polycarp, and the Acts of the Apostles.

Jesus and his first disciples were Jews, and for several centuries after his death Christians of Jewish origin were a significant presence both inside and outside of the land of his birth. The history of Jewish Christianity in the first few Christian centuries begin with Jesus brother James, the leader of the Torah observant, the predominant faction in the Jerusalem 'mother church' until its dispersal in the Jewish revolt of 66-73 CE, and perhaps even afterwards. James continues to be a model of Torah piety in the second-third century Jewish Christian sources embedded in the fourth-century Pseudo-Clementine literature. James and Peter were important figureheads, but they themselves were only the tip of a huge Jewish Christian iceberg that is mostly invisible to us because of the eventual triumph of Gentile Christianity. Paul himself, in his battle against it, provides compelling evidence of its power, for example in his letter to the Galatian Christians.

The Pentecostal scene in Jerusalem, as depicted in Acts 2:9ff, has Peter preaching to Jews who have gathered in Jerusalem from the Diaspora. Antioch is depicted by Paul as well as by the author of Acts as the fons et origo of 'Gentile Christianity': here the process of Christian self-identification is declared to have its beginning. Some sort of control over the estimate of the social spread of Christianity in the generation between the thirties and the sixties might be sought in the onomastics of the Pauline connexion, from an examination of the sixty-six named individuals in the genuinely Pauline documents or of the full register of some ninety-seven names if one includes in the tally the pastorals as well. All known is that Claudius 'expelled from Rome Jews who were causing continual disturbances at the instigation of Chrestus'. Tacitus is the original source to connect the fire of Rome under Nero with Christians.