A dynamic model of church growth and its application to contemporary revivals

The Christian church has grown substantially since its beginnings in the first century AD, with much of that growth coming through conversion into the church. This paper sets up a dynamical model of such church growth, based on the methods of systems dynamics, capable of giving qualitative analysis and quantitative simulations of growth. The model investigates the claim that conversion growth is driven by a subclass of church members called enthusiasts who alone are active in the conversion of others. These enthusiasts make contact with unbelievers leading to some being converted. Some of these new converts also become enthusiasts. A further claim is that enthusiasts only retain their conversion potential for a fixed length of time after which they become inactive church members playing no further part in recruitment. The effect of enthusiasts on the growth of the church can be quite dramatic, following a similar pattern to that of an epidemic. Although substantial growth is possible it eventually “burns” itself out due to lack of enthusiasts. This behaviour is similar to the patterns of growth seen in religious revivals of the past. The model is applied to such recent phenomena as the Toronto Blessing and the Alpha course.