Activists are believers who contribute to the life of the church. They are a more general group than enthusiasts, whose specific role is to make converts. There will be many other active people in the church who are not involved in conversion. The Limited Enthusiasm Model is extended to include active believers. This extended model will be useful in sociological models of church growth, dealing with issues such as spiritual life and institutionalism.
The central hypothesis of the limited enthusiasm model is that conversion growth in the church is driven by a subgroup of church members called enthusiasts. New converts become new enthusiasts. The analogy is with the spread of a disease, where the enthusiasts are “infected” believers passing the faith on to unbelievers who catch the “disease” of religion. There are also activists within the church who, although not actively involved in recruitment, are engaged in other areas of church life.
Church growth is limited as enthusiasts fail to reproduce themselves from a shrinking pool of potential converts. The church will consist of a balance of enthusiasts, other activists and inactive believers.
System Dynamics Model
Stocks and Flows
This model has three types of Christians:
- Enthusiasts – those active in conversion;
- Active Believers (Activists) – those active in the church but not in conversion. They are “non-recruiting” activists.
- Inactive believers – who play no part in conversion or any other aspect of church life.
These three types of church people are represented by three stocks in figure 1. Enthusiasts will also be active in other aspects of church life. Thus, the total activists are the sum of enthusiasts and active believers. The other stock represents the number of unbelievers.
Feedback
Unbelievers convert to believers through contact with enthusiasts who have “spread the faith” to them, loops R and B1. Some new converts become enthusiasts, some become activists who do not recruit, and the remaining converts become inactive believers. A believer is an enthusiast for only a limited time before ceasing to spread the faith, loop B2. They either remain active in other aspects of church life, or become completely inactive.
Active believers only remain active for a limited time before becoming inactive, loop B3. This time is likely to be much longer than the duration of enthusiasm, as many active Christians are active for most of their lives.
In this simplified model, only inactive believers leave the church, loop B4. After becoming unbelievers, they are open to re-conversion driving future growth, loop R2. The delays in the process cause long-term oscillations in church numbers.
The model may be enhanced with births, deaths, hardened unbelievers and reversion from all categories. See the Demographics model. The enhanced model enables more accurate calibrations, though the general model behaviour is the same.
Equations
The system dynamics model reduces to four differential equations:
Parameters
The model has eight parameters.
| PARAMETER | DESCRIPTION |
|---|---|
| Reproduction Potential Rp | This is the number of unbelievers converted and made enthusiasts, through one existing enthusiast, given the whole population are unbelievers. It measures how much enthusiasts can “reproduce” themselves from the pool of unbelievers. |
| Duration of Enthusiastic Phase τi | The average time an enthusiast is active in conversion before they become an activist who does not recruit. |
| Duration of Active Phase τa | The average time spent as an activist is active before becoming inactive. |
| Fraction of Converts Enthusiast g | The fraction of new converts who become enthusiasts. The remaining people become either active or inactive believers immediately after conversion. Describes the discipleship of new converts. |
| Fraction of Converts active f | The fraction of new converts who become activists. The remaining people become inactive believers immediately after conversion. Describes the discipleship of new converts. |
| Fractions of Enthusiasts who become Inactive h | The fraction of enthusiasts who become inactive after their enthusiastic phase rather than continue as active believers. Describes the discipleship of enthusiasts. |
| Leaving Rate α | The total rate at which inactive believers leave the church. |
| Initial Fraction of Church Enthusiast | The fraction of the church that are enthusiasts at the start of the model. |
| Initial Fraction of Church Activist | The fraction of the church that are activists at the start of the model. |
Results
There are implications for the long-term growth and decline of the church. Like the basic limited enthusiasm model, there is a revival growth threshold over which the church will see rapid growth, figure 2. However, there is also an extinction threshold, equal to unity, under which the church will decline to zero members or attenders.
The peak in the total church is later than that of the total activists (including enthusiasts), figure 3. This delay will have significance when sociological variables are included. Those driven by the whole church or by inactive believers will take longer to respond than those driven by the church activists.
Significance of Activists
Active believers, the activists, contribute to the life of the church. For example, they may build the church’s spiritual life or prevent the church from becoming institutionalised. Effective discipleship will aim to increase the number and proportion of active believers in the church. Their full role is utilised when the limited enthusiasm is extended to encompass sociological variables, such as spiritual life.
Further Results
References
The concept of activists comes from modelling the growth of political parties. See:
- Jeffs R.A., Hayward J., Roach P.A. & Wyburn J. (2016). Activist Model of Political Party Growth. Physica A: Statistical Mechanics and its Applications, 442, 359-372. arXiv:1509.07805. Physica A.
- Hayward J., Jeffs R.A. & Roach P.A. (2020). A Supply and Demand Model of Political Party Growth. Presented at the 36th International Conference of the System Dynamics Society, Virtual Bergen, July 2020.