The church growth strategy in the New Testament church is simple: preach the Word, shepherd the flock. Some would call this no strategy, but that would be mistaken. The numbers are obviously important to Luke who writes for Theophilus and the church community in the book of Acts.
The church in Jerusalem began with 120 people, but after Peter’s sermon on Pentecost, we’re told 3000 were added (Acts 1:13; 2:41). Then, an additional 5000 men, not including women and children came in (4:4). Even after the sobering deaths of Ananias and Sapphira, “more than ever believers were added to the Lord, multitutudes of both men and women” (5:14). Again, the church “disciples were increasing in number” (6:1), so they appointed deacons. And it “multiplied” some more (6:7).
Lest we think this was confined to Jerusalem, the church in Judea, Galilee and Samaria “grew in numbers” (9:31). All the residents of Lydda and Sharon who saw Peter “turned to the Lord” (9:35). When people in Joppa heard, “many people believed in the Lord” (9:42). Increase of “great numbers” are mentioned three times about the church in Antioch (11:21, 24, 26). “A great number of Jews and gentiles believed” at Iconium when Paul first visited there (14:1). At Derbe it was “a large number of disciples” (14:21), and in sum “the churches…grew daily in numbers” (16:5). The second journey produced similar results with “a large number of God-fearing Greeks and not a few promienent women” being added ot teh church (17:4). Berea was no different (17:12). Demetrius complains about the “large numbers of peole here in Ephesus and in practically the whole province of Asia” Paul had convinced (19:26), apparently enough to put pagan religious craftsmen out of work!
To say the growth strategy was simple is not to say it was easy; it also resulted in jail time and many stripes. But the apostles preached to the unconverted and they were heard. Luke consulted with those who knew how many heard, and it’s a regular part of his narrative. This tells us that numbers matter and we ought to strive for God’s blessings in God’s ways.