The following quote is in response to charges made by Celsus, a pagan philosopher, against Christianity. (By the way, Celsus’s work is actually a very interesting read… strong recommendation.) This is part of the response from Origen of Alexandrai (185-253AD, more or less):
But since he is manifestly guilty of falsehood in the statements which follow, let us examine his assertion when he says, “If all men wished to become Christians, the latter would not desire such a result.” Now that the above statement is false is clear from this, that Christians do not neglect, as far as in them lies, to take measures to disseminate their doctrine throughout the whole world. Some of them, accordingly, have made it their business to itinerate not only through cities, but even villages and country houses, that they might make converts to God. And no one would maintain that they did this for the sake of gain, when sometimes they would not accept even necessary sustenance; or if at any time they were pressed by a necessity of this sort, were contented with the mere supply of their wants, although many were willing to share (their abundance) with them, and to bestow help upon them far above their need. At the present day, indeed, when, owing to the multitude of Christian believers, not only rich men, but persons of rank, and delicate and high-born ladies, receive the teachers of Christianity, some perhaps will dare to say that it is for the sake of a little glory s that certain individuals assume the office of Christian instructors. It is impossible, however, rationally to entertain such a suspicion with respect to Christianity in its beginnings, when the danger incurred, especially by its teachers, was great; while at the present day the discredit attaching to it among the rest of mankind is greater than any supposed honour enjoyed among those who hold the same belief, especially when such honour is not shared by all. It is false, then, from the very nature of the case, to say that “if all men wished to become Christians, the latter would not desire such a result.”Against Celsus, by St. Origen, Book III, Chapter 9.
In the response to the charge by Celsus that Christians don’t really want all people to become Christians, Origen points out that Christians do desire as much as possible to disseminate their faith throughout the world. He then talks about a certain class of Christian who travels from city to village to house to share the gospel message. The description fits the early church picture of an Apostle. As von Harnack noted, the two pimary characteristics (as indicated in the Didache, Shephard of Hermas particularly) of an apostle is mendicancy and zealous evangelizing. Over time, the term Apostle (which as time went on became more associated with “The Twelve”) fell out of fashion for these individuals and so would be usually called Evangelists. Later, the Latinized term, Missionary became popular. Here with Origen the terms he used were “teachers of Christianity” and “Christian instructors.”
What makes this quote import is that it was written in the third century when missionaries or apostles had seemed to have disapeared. Part of this was because of the movement towards power and offices being fully centered in the church… such that people such as Bishops Polycarp and Cyprian would be described as having a certain ‘apostolic’ authority, leading toward the later identification of apostle as being a position inside of the ecclesiastical hierarchy rather than outside. Such great focus was placed on the work within the church in the 2nd and 3rd centuries that if it were not for Origen and later Eusebius we would hardly know of their existence. Even with them, with the exception of Pantaenus, they are missionaries who remain unnamed and unhonored. Strangely, that was the point of Origen. These people shared the Gospel without material reward. If some Christians of means do indeed help them with food or shelter in their travels. this small bit of honor is more than balanced by the dishonor heaped on them by the world around them.