As a church denomination grows, it needs to develop structures to support itself: full-time ministers, training, buildings, governing bodies etc. However, the larger the church becomes, the greater effort is needed on maintaining the institutional structures; thus, less effort is available for conversion and recruitment.

The model predicts that growth comes to a halt and that without interventions to dismantle some denominational institutionalism, the church denomination eventually dies due to institutionalised lethargy.

This is a sociological model whose purpose is to understand church growth and decline using principles from the sociology of organisations and religion.

For more model details see Assumptions and Parameters.


As a church denomination grows, resources are needed to support its organisational structure. Such resources, once set up, need to be maintained. They may acquire their own reasons to exist and lose their connection with the church’s recruitment and conversion mission. It follows that the resources tend to be easy to construct but hard to dismantle. Thus, they continue to be maintained long after their usefulness to the mission has waned. They cannot be easily scaled back just because the numbers in church decline.

The greater these institutional resources, the more institutionalised the church. This will be represented by a single soft variable “Institutionalism”.

Examples of institutional resources include physical buildings, the number of paid ministers, requirements for ministerial training, centralised leadership and the expectations of full members. A more complete list is on the Further Model Details page.

System Dynamics Model

Unbelievers are added to the church according to the size of the church (R1) but reduced according to institutionalism (B2), figure 1. Church members leave at a constant rate per person (B1). Institutionalism is generated according to the size of the church (B2). Institutionalism is easier to generate as it grows (R2) but becomes harder to produce as it approaches capacity (B3). Attempts to reduce institutionalism occur at a constant per capita rate (B4).

Figure 1

The leaving feedback loop B1 has a constant impact. However, because loop B2 reduces the recruitment effectiveness of the church members, the reinforcing loop R1 has a diminishing impact on recruitment. The limit to church growth is reached when the recruitment rate matches the leaving rate, after which the church declines.

Scope of Applicability

The Institutional Model is applied to a whole denomination, or a collection of national denominations, and is less applicable to an individual congregation. It is similar in form to the Self-Enhancing Resource Model that models limits to congregational growth.

Results of the Institutional Model

Church starts by growing (R1), with institutionalism also growing (B2 and R2), see figure 2. However, church growth slows as the impact of B2 reduces that of R1. Church growth slows as the impact of R1 falls below the combined impacts of B1 and B2. Eventually, recruitment falls below the leaving rate and church declines, curve 1, figure 2. Without intervention, then institutionalism declines too slowly to prevent the church from becoming extinct, curve 2.

Figure 2

See Further Institutional Model Results.