NOTES for Act 11:19-30
Clearly, the conversion of Cornelius was only the first stage of the Gentiles' entry into the Church. Most remarkable of all, these recent pagans themselves actively join in the expansion of the Kingdom, and therefore of the Church: they begin bearing witness to their own people. Jewish Christians, even after scattering through the territories adjoining Judea, evidently followed strictly the principle the Savior had observed during His earthly ministry. They bore witness only to Jews, helped by the fact that Jewish communities existed at that time in every reasonably large city of the Roman Empire. Meanwhile, former pagans, upon converting and entering the Church, began by bearing witness to those around them, who were pagans just as they themselves had been until quite recently.
The somewhat isolated character of the Jewish world probably played a part here: Jews generally felt more at ease among their own people, as they had in every age, and it was also easier for them to bear witness in their own surroundings. The same could be said of newly converted Gentiles: they naturally found it easier to speak the same language as their own people than did Jews living in the rather closed world of the Jewish quarter. Meanwhile, God used all these differences to bring as many people as possible into the Kingdom.
Eventually, the mission among the Gentiles became noticeable to the Church as a whole. These recent pagans even acquired their own Greek name for themselves: Christians—in Greek, “Christians” means “Messianists.” At that time the Church took the form of a religious brotherhood, and such brotherhoods were essentially a communal movement, usually with a council of elders but without a rigid structure or hierarchy.
Naturally, the Jerusalem community enjoyed special authority in the Church. It was no accident that a respected representative of that very community went to Antioch in Syria to see the new converts for himself and spend time with them. Once there, he stayed for a year: what he saw seemed that important to the Church. Thus, alongside its Jewish, or religious, component, the Church acquired a secular one, which in the language of the New Testament books could be called Gentile.
This is hardly surprising: the Kingdom does not depend on any religion, and one need not be a religious person to share in its life. Trust in Christ and readiness to follow Him are enough. Just as Cornelius did first, and then other former pagans, who became inhabitants of the Kingdom and called themselves Christians before the world.