"Despite uncertainty about numerous aspects of primitive Christianity, the sources are unanimous in reporting certain basic traits. Among these is an enthusiastic dedication to missionary activity. There was, to be sure, a protracted and often bitter debate about whether the mission should focus exclusively on Jews (“Go nowhere among the Gentiles,and enter no town of the Samaritans, but go rather to the lost sheep of the house of Israel” – Matt 10:5f; cf. also the story of the Syrophoenician woman in Matt 15:21–28) or should include Gentiles as well (“Go therefore and make disciples of all nations . . .” – Matt 28:19!). Even among those who advocated a universal calling, there was disagreement about the conditions under which Gentiles could embrace the faith. Should they assume the full burden of the Mosaic Law (“But some believers who belonged to the party of the Pharisees rose up, and said, “It is necessary to circumcise them, and to charge them to keep the law of Moses.”’ – Acts 15:5) or just a partial burden (Acts 15:19f)? Still others, like Paul, maintained that allegiance to the Christ meant freedom from the Law altogether (Galatians, passim). But transcending these disagreements was a consensus that a primary obligation of the community as a whole was to proclaim the gospel of Christ in the world. More than any other cult in the Roman Empire, Christianity was a missionary faith and, of course, owed its ultimate status in the empire to the success of its mission."
Although I am uncomfortable with the thesis of this article as a whole, which sees the evangelistic efforts of the early church as an example of cognitive dissonance related to the perceived failure of the kingdom to appear, the quote above is a helpful reminder of the evangelistic priority in the early church.
John G. Gager, “Christian Mission and the Theory of Cognitive Dissonance,” in Social-Scientific Approaches to New Testament Interpretation, ed. David G. Horrell (Edinburgh: T & T Clark, 1999), 179.