Missionary outreach by friendly contact looks somewhat different when one reflects on what is known about friendly contact in metropolitan neighborhoods; the majority of such contacts are with people of similar social and economic position; association by level of achievement is the dominant principle of informal relations. This means that the antennae of the congregation are extended into the community, picking up the wave lengths of those who will fit into the social and economic level of the congregation; the mission of the church is actually a process of informal co-optation; the lay ministry is a means to recruit like-minded people who will strengthen the social class nucleus of the congregation. Churches can be strengthened through this process of co-optation so long as the environs of the church provide a sufficient pool of people who can fit the pattern of economic integration; once the pool of recruits diminishes, the congregation is helpless -- friendly contacts no longer keep it going.

The transmutation of mission to co-optation is further indicated by the insignificance of educational activities, worship, preaching, and publicity in reaching new members. The proclamation of the churches is almost totally confined to pastoral contacts by the clergy (17.3 per cent of new members) and friendly contacts by members (over two thirds if organizational activities are included). Publicity accounted for 1.1 per cent of the initial contacts with new members. In general, friendly contact with a member followed by contact with a clergyman will account for a major share of recruitment by the churches, making it quite evident that the extension of economic integration through co-optation is the principal form of mission in the contemporary church; economic integration and co-optation are the two methods by which Protestants associate with and recruit from the neighborhood. The inner life of congregations will prosper so long as like-minded people of similar social and economic level can fraternize together; the outer life of congregations -- the suitability of the environment to their survival -- will be propitious so long as the people in the area are of the same social and economic level as the membership. Economic integration ceases when the social and economic statuses in an area become too mixed or conflict with the status of the congregation. In a rapidly changing society congregations will run into difficulties repeatedly, since such nice balances of economic integration are hard to sustain in the metropolis for more than a single generation. The fact that metropolitan churches of the major denominations have moved approximately every generation for the last hundred years becomes somewhat more intelligible in the light of this struggle to maintain economic balance. The expense of this type of organization in religious life, when one recalls the number of city churches which deteriorated beyond repair before being abandoned, raises fundamental questions about the principle of Protestant survival in a mobile society; nonetheless, the prevalence of economic integration in congregations illumines the nature of the Protestant development.