Although the church had no legitimate status in the Roman world, it was able to evangelize and expand by means of public proclamation or preaching, especially through the medium of the synagogue.
Preaching
The early church could not conduct public worship on the scale to which North American Christians are accustomed. Especially in the Jewish homeland, the church’s situation was similar to that of today’s believers in Muslim countries, where any public expression of Christian faith is considered highly provocative and even illegal. The cultural pluralism of Greek-speaking areas afforded a less restrictive atmosphere, but because it lacked buildings of its own the infant church was largely limited to gathering in private homes. Nevertheless, unbelievers did attend the Christian assemblies (1 Cor. 14:23).
The unbeliever’s first exposure to the gospel, however, was more likely to come from the preaching of the apostles or evangelists of the faith. Preaching (kērugma) was a public activity intended to evangelize people who had never heard the message of the new covenant and of the lordship of Christ; the word means “announcement” or “heralding.” Thus preaching in the New Testament church was distinguished from teaching (didachē), the exposition of scriptural truths in the gathering of believers. Preaching was an opportunistic activity; that is, it occurred whenever a suitable occasion arose. The healings and deliverances performed by the apostles were significant openings for evangelism (Acts 3; 9:36–43; 19:11–20). The apostles used the synagogue service as a platform for the proclamation of Jesus as the Christ, reaching through this medium not only Jews but Gentiles who frequented the synagogue, known as “God-fearers” (phoboumenoi) in New Testament terminology (Acts 10:2, 22; 13:16, 26; cf. 18:7). Meeting opposition in the synagogue at Ephesus, Paul expounded the faith through a series of public meetings in a rented lecture hall (Acts 19:8–10), and the Acropolis at Athens offered him a forum for public debate with Greek intellectuals (Acts 17:16–34).
Apologetic Literature
The production of literature defending the Christian gospel became important in the second century through the work of spokesmen such as Justin Martyr (c. 100–165). Some New Testament literature is already of this “apologetic” type, particularly the two-volume work by the physician Luke, consisting of his Gospel and the Acts of the Apostles. The work is written for the public as well as for the church and is dedicated to a man named Theophilus (Luke 1:3; Acts 1:1), who may have underwritten its publication. In this work, Luke shows how the church emerged from its Jewish matrix to become a recognized entity within the Greco-Roman world; his story of the church begins in Jerusalem and ends in Rome. While not concealing the Hebraic element in the Christian heritage, Luke takes pains to record the increasing Gentile involvement in the expanding movement, stresses Paul’s Roman citizenship at critical points, and portrays certain government officials as knowledgeable of the Christian way, or at least not hostile to it (Acts 18:12–17; 19:35–41; 23:16–31; 24:22–26).
Public Obligations
In social services, the church was predominantly concerned with its own constituency. However, the admonition to “do good to all men” suggests an outreach not limited to “those who are of the household of the faith” (Gal. 6:10). Christians were expected to pay their taxes and to honor civil authority as given by God for the maintenance of order (Rom. 13:1–7). Whatever the situation in later centuries, in the New Testament period most opposition to the Christian movement came from Jewish rather than Roman authorities, and in fact, the policies of the state were usually helpful in enabling the church to continue its activities.