Justo Gonzales says (The Story of Christianity, vol. 1, 98-99):
The enormous numerical growth of the church in its first centuries leads us to the question of what methods it used to achieve such growth. The answer may surprise some modern Christians, for the ancient church knew nothing of “evangelistic services” or “revivals.” On the contrary, in the early church worship centered on communion, and only baptized Christians were admitted to its celebration. Therefore, evangelism did not take place in church services, but rather, as Celsus said, in kitchens, shops, and markets. A few famous teachers, such as Justin and Origen, held debates in their schools, and thus won some converts among the intelligentsia. But the fact remains that most converts were made by anonymous Christians whose witness led others to their faith. The most dramatic form taken by such witness was obviously that of suffering unto death, and it is for this reason that the word “martyr,” which originally meant “witness,” took on the meaning that it has for us.
I am not endorsing the centrality of communion over preaching which Gonzales says the early church did. I want to think more about that and what went on with communion, like a rehearsal of the biblical gospel to keep it central, in which case I’d have no problems with it being central to the corporate gathering. But notice where church growth and gospel spreading activity happens. It happens where people live life in the world. And who equips such people to do that type of ministry and love of modeling and communicating the gospel in words understandable to their culture? Paul would say the pastors and teachers (along with the apostles, prophets, and evangelists).
(ESV) Ephesians 4:11 And he gave the apostles, the prophets, the evangelists, the pastors and teachers, 12 to equip the saints for the work of ministry, for building up the body of Christ…