Reactivation of Believers

The central hypothesis of the limited enthusiasm model is that conversion growth in the church is driven by a sub-group of church members called enthusiasts. New converts become new enthusiasts. The renewal model extends this model to allow for existing inactive believers to be “renewed” in the faith and also become 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 and infecting inactive believers, enabling them to be agents in conversion.

The model predicts a threshold of revival-growth that depends on two factors: the size of the community that remains unconverted, and the rate at which inactive believers are renewed. The more renewal, the lower the revival threshold and the more likely rapid conversion growth can occur. Renewal of faith is a key driver of church growth.

Model Results


The model consists of three groups of people: unbelieversenthusiasts who alone are responsible for spreading the faith, and inactive believers. If demographic effects are included, then unbelievers are split into those open to conversion and those hardened against.

The renewal model is built on the Limited Enthusiasm model, and the Demographics extension, where the assumptions are explained further.

The dynamic hypotheses are:

Dynamic HypothesisDescription
Conversion Through EnthusiastsEnthusiasts are responsible for spreading the faith, i.e. conversion to the church. The more they convert, the more enthusiasts. This accelerates growth. Spreading the faith can be by numerous means.
Loss of EnthusiasmAfter a period of time, enthusiasts lose their potential to convert. This slows and limits growth.
Diminishing Susceptible PoolAs people are converted the effectiveness of the enthusiasts on the remaining unbelievers become less as proportionally more of the enthusiast’s time is spent on believers. This slows growth.
Not All Converts Become EnthusiastsNot every convert becomes an enthusiast. Some become immediately inactive.
Renewal of Inactive BelieversEnthusiasts are responsible for making inactive believers enthusiasts through contacts within the church. The more believers they renew, the more enthusiasts made. This accelerates the production of enthusiasts and enhances conversion growth. Renewal can be through many means.
DemographicsThere are many assumptions connected with births, deaths, leaving the church, reversion, softening and hardening of unbelievers, as in Demographics model.

System Dynamics Model

The renewal assumption modifies the existing limited enthusiasm model by adding an extra flow from the inactive believers to enthusiasts, see the stock-flow diagram, figure 1.

Figure 1: Limited Enthusiasm Model with Renewal

Growth is driven by the reinforcing loop R1 where enthusiasts are reproducing themselves through conversion. The feedback: more enthusiasts, more conversions, more enthusiasts, gives exponential growth. Growth is opposed by B1, which reduces conversions, thus slowing the exponential growth. When conversions have been reduced below the number who lose enthusiasm, B2, the number of enthusiasts starts to decline, and therefore church growth slows and eventually halts.

The production of enthusiasts is enhanced directly by the renewal, loop R2, which in turn accelerates conversion growth. The production of enthusiasts is also enhanced indirectly through loop R3, where those who lose enthusiasm are open again to renewal. Renewal is opposed by B3, as the pool of potential inactive believers depletes.

What is Meant by “Spreading the Faith”?

All aspects of conversion and spreading the faith are discussed in the limited enthusiasm model.

How Do Believers Get Renewed?

  1. The believer sees a spiritual life in other Christians far more appealing than their own. Their dissatisfaction with their spiritual state leads them to seek Jesus Christ and ask fora similar quality of life. That quality of life becomes noticeable to others.
  2. The believer comes into contact with organisations who promote a more vibrant form of Christianity: “deeper life”, “spirit filled” etc, or a courses such as the Alpha Course or Christianity Explored. Perhaps they are taken by friends to conventions such as Spring Harvest, or New Wine. The subsequent life changes, or even identity with such organisations, has impact on their unbelieving friends.
  3. Some of the “believers” were not truly converted in the first place. Although they belong to the church they may have joined for social reasons rather than spiritual ones. Their contact with enthusiasts within their church has become the means of their conversion.
  4. The “renewal” may be a burden for the state of the lost impressed on them by some other Christian, launching the believer into evangelistic activity. This may come through participation in evangelistic training courses or discipleship classes.


All demographic aspects are discussed in the demographics model.

Model Parameters

The behaviour of the model is controlled by several parameters that reflect the church’s effectiveness, and the response of society:

Reproduction PotentialThis is the number of unbelievers converted, and made enthusiasts, through one existing enthusiast, given the whole population are unbelievers. It measures how much an enthusiast can “reproduce” themselves from the pool of unbelievers.
Renewal PotentialThis is the number of inactive believers made enthusiasts, through one existing enthusiast, given the whole church are inactive. It measures how much an enthusiast can “reproduce” themselves from within the church.
Duration of Enthusiastic PhaseThe average length of time and enthusiast is active in conversion before they become an inactive believer.
Fraction of Converts EnthusiastThe fraction of new converts who become enthusiasts. The remaining people become inactive believers immediately on conversion.
Initial Fraction of Church EnthusiastThe fraction of the church who are enthusiasts at the start of the model.
Demographic ParametersBirth and death parameters, leaving and reversion rates, hardening and softening rates. See Demographics model.

Results of the Limited Enthusiasm with Renewal Model

It is possible for a church with an inadequate reproduction potential to see growth if there is sufficient renewal. However, such a recovery depends on there being a critical mass of church size and a critical mass of enthusiasts. Thus even a church which would have been under the extinction threshold can have revival growth if there is sufficient renewal. Renewal, not evangelism, is the key to church growth.

See Renewal Results.