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Church Growth Modelling

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Model Construction

Institutional Model

Church recruits in proportion to size, but recruitment rate reduced by institutionalism which grows as church grows.

Extended Institutional Model

Used for application to GB Methodist Church.
Growing population, delays in cause and effect, internal pressures for institutionalism.

Model Results

Decline Caused by Institutionalism

Related Blog

Institutionalism and Church Decline

Response to comments by others on the negative effects of institutionalism on church growth.

The Rise and Decline of British Methodism

Application of the Institutional Model of Church Growth.

The Rise and Fall of British Methodism

Application of the Institutional Model

The British Methodist church started as a renewal movement within the Church of England in the mid 18th century. It rose rapidly through revival to the second half of the 19th century, after which it has declined with increasing speed. Early Methodism was marked by spiritual life and spontaneity, even after it became established as a separate church around the turn of the 18th and 19th centuries. However as the denomination grew it became structurally more organised. As such it is a candidate to test the Institutional Model of Church Growth which hypothesises that decline is caused by rising institutionalism.

Question: Does rising institutionalism explain the rise and fall of the British Methodist church?

Data Fit

For the model to be a suitable explanation of behaviour then at the the minimum it must fit the data. Membership data was taken for England, Scotland and Wales from 1767, the earliest known data, to 2014. Ireland was excluded due to poor population data in the early period, and the later political division of the country. The earliest Methodist membership figures are taken from Currie et. al. (1977) , table A3, pp. 139-144. The various Methodist church divisions are combined together so that they can be compared with the later united church. Later data is taken from publications by Brierley and figures released by the Methodist church.

The optimized fit of the membership data to the model is given in figure1. The model captured the general shape of the data well. Two features the model cannot reproduce: the disruption around 1850 when a major church division took place; and the variable membership around the two world wars. Using estimates of the aging of the church population in the last 30 years helps captures the linear downward trend, though as will be seen, the model does not accurately extrapolate further. Optimization was achieved using Vensim software.

Figure 1: Institutional Model of Church Growth Compared with GB Methodist Membership

Refinements were made to the model allowing for delays in the effect of church size on institutionalism, and in the effect of institutionalism on conversion growth. An additional effect was added to capture the desire for institutionalism among ministers and members. Population data, birth rates and death rates were used from the Office of National Statistics and various historic sources. From these births, and by comparison with the Welsh Methodists, the birth rates for the church were estimated allowing for a younger church in the early years, and an older one more recently. A similar method was used for the church death rates using the church's own estimates where available. For further details see the full extended model and calibration.


A second test of the model is to examine the behaviour of Institutionalism. The initial value was set low, reflecting early days of the Methodist movement. Figure 2 shows institutionalism rises rapidly, then slowing in early 1800 when the church had become more established with professional clergy and governance. The effect on membership is delayed, which does not start declining until institutionalism is saturated.

Figure 2: Methodist Church Membership Compared with Church Institutionalism

It should be noted that the last 50 years of membership growth before the peak in 1923 represents GB population growth, figure 2. Comparing membership data with the GB population shows the percentage share peaks around 1870, figure 3, the market share of the Methodists falling after that date. This is the date when revivals largely ceased in the UK and it could be argued that rising institutionalism stifled revival and thus conversion growth. A similar effect has been shown for the Welsh Calvinist Methodists.

Figure 3: Methodist Membership as a Percentage of the GB Population.

The model has been extrapolated in both figures 2 and 3. It is seen the decline slows down. This is likely to be a flaw in the model underestimating the deaths in a declining and aging church population. Without an exact knowledge of the age profile of the church over the last 20 or so years it is not possible to reliably correct for this effect.

Rates of Change

A further test of the model is to compare the inflows and outflows for the church. Figure 4 compares biological growth, those born into the church, with conversion, i.e. recruitment, deaths and leaving. Conversion, curve 1, is the largest rate of change up to 1930 when it is matched by leaving rate, curve 2. This happened because conversions stop increasing in the 1860s when the period of widespread revival has ended, whereas the leaving rate carried on increasing as church membership increased. It is clear that the failure to increase conversions with rising church size is the primary reason why growth slows and decline sets in. From the mid 19th century onwards church become proportionally less active in recruitment as it became more institutionalised.

Figure 4: Additions and Removals from the GB Methodist Church.

From 1767 into the nineteenth century the birth and death rates are evenly matched. The reason the number born into the church is not much higher than deaths is because it has been assumed that only 50% of those born to church members are retained in the church, a figure measured from the Welsh Calvinist Methodist data. At the end of the 19th century a rapid rise in population growth and fall in national death rates means the birth rate exceeds the death rate. The position is reversed in the early 20th century due to falling national birth rates, the effects of World War 1 and aging congregations. It is clear that falling national birth rates has contributed to Methodist decline, although falling conversion is the primary cause.

For the last 35 years the church death rate is the largest rate of change. The church still only converts as many as leave. Thus the effects of aging on biological growth and deaths is now the major cause of Methodist decline.


However the parameters of the model are adjusted the early growth of the church can only be explained by a high conversion rate, a level that was not sustained. The rise of institutionalism provides a satisfactory explanation of the changes in Methodist membership and falling conversion, however it should be stressed that this does not mean that other explanations are not equally as suitable. In particular this model contains no mechanism of revival, and it is clear that the end of revivals occurs at a time of a significant slow down in church growth. However the spirit of this type of model does not examine such fine details as a model of revival would contain, thus in that spirit the model is deemed an acceptable explanation for the Methodist church growth and decline.

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Church Growth Modelling