Church Growth Modelling is a research project that uses the techniques of mathematical sociology and system dynamics to understand the growth and decline of the Christian Church.

The models give valuable insights into the way the churches grow or decline at either a congregational, denominational, national or international level. They are particularly helpful in describing the growth dynamics in times of revival.

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This website is aimed at church practitioners who wish to understand the growth of their churches and enhance that growth. It will also be of interest to academics and researchers looking for a quantitative understanding of the spread of religion

Origins of Project

The idea that church growth could be modelled with mathematics came to me from two sources. In the early 1990s, I was studying, by correspondence, for a certificate in Christian studies. One module was on church growth and evangelism. As much as I enjoyed it and analysed my own church, I was left frustrated that the level of analysis gave me little understanding of how the attendance numbers in my church changed. There was no theory to test the data against.

Then, in 1994, the Toronto Blessing occurred. The movement started in the Toronto Airport church in January of that year, and a steady stream of Christians from the UK visited the church to “bring back” the blessing. The movement hit the UK in the summer, helped by some media exposure, and particularly the rise of the internet. Someone not too sympathetic to the movement made the comment, “it is spreading like a disease”. That got me thinking. There were well-established models for the spread of the disease. Could they be adapted to the growth of a church, especially in times of revival? Although controversial, the Toronto Blessing had many of the hallmarks of revival.

SIR Model

I took the standard “SIR” model for the spread of disease and reconstructed it to apply to the church. The “infected” Christians became a particular category of people who passed on the faith to others. Later, I called these people enthusiasts after the nickname given to the Methodists in the 18th century. I applied the model to the Welsh Revival of 1904/5 and wrote it up as a technical report for my university in 1995.

The report was widely circulated to several Christian agencies and churches. It was even quoted in Pete Greig’s Awakening Cry. After comments from people, I was encouraged to submit it for publication. I chose the journal of mathematical sociology because of its interest in applications of maths. But I wondered if an application to the things of God was one application too far! I had a very kind anonymous referee who encouraged me to read various works on the sociology of religion and then re-submit the paper. Although this took a year to achieve, it improved the paper dramatically, and it was published in 1999. Over the years, I have had over 400 requests for copies of the paper, many from non-mathematicians.

Since then, the model has been extended. I have moved into system dynamics because of its powerful model-building capabilities and because it is very presentable to non-mathematicians. Students, both undergraduate and postgraduate, have used the work and applied it to other social phenomena. But it took a move of God in 1994 to start the work off.

The Work of Others

It turns out that Lionel Penrose, a statistician, had a similar idea back in 1952 but had not developed it mathematically (Penrose 1953). Also, a research group had already applied the epidemic analogy to a different social situation, the spread of riot behaviour (Burbeck 1978). But I never knew that when I started my first model. Since the 1990s, research in social epidemics has exploded with applications to fashions, crime, the rise of the Internet and the persistence of minority languages. A vindication that mathematical modelling can help understand complex human behaviour.