In the church growth models, “enthusiast” is the name given to the Christian believer who is responsible for bringing unbelievers to faith. “Responsible” in this context means the human point of contact where the faith is passed on. It does not refer to the supernatural work in the heart, which is God’s responsibility! But we know God spreads the gospel through people. Those who spread it, so that others are converted, are called enthusiasts.

Some of these converts will themselves become enthusiasts, and in turn, make more converts. Thus, the enthusiast is an “infected” Christian, passing on the faith a bit like the way a disease is passed on. Of course, enthusiasts are not effective indefinitely. Just like people with a disease, the infectious period of an enthusiast is limited. Eventually, they either run out of contacts, run out of enthusiasm, or find so much else to do in the church they spend too little time in evangelism and witness.

Limited Enthusiasm Model

The above scenario describes the limited enthusiasm model [1]. It follows that church growth is very dependent on the enthusiasts within the church. A church needs enthusiasts – and should set about generating them! But what is the best way – to have more enthusiasts or more effective enthusiasts? Should they produce quantity or quality?

The advantage of having a mathematical model is that computer simulations can be used to investigate different strategies. First, I will look at the effect of changing the initial number of enthusiasts on the growth of the church. Then do the same by changing the effectiveness of the enthusiasts, and comparing the results.

Increase the Quantity of Enthusiasts

Firstly, let the initial number of enthusiasts be increased, whilst their effectiveness remains the same. Perhaps the church has engaged in a training programme. Perhaps it has more of its congregation involved in an outreach course like Alpha or Christianity Explored. Figure 1 shows the effect of changing the quantity of enthusiasts on church growth over 50 years. The high percentage growth is because the church starts small.

Graph: Change in church numbers when increasing quantity of enthusiasts
Figure 1: Effect on church growth of increasing the quantity of enthusiasts

The good news is that the more enthusiasts, the more church growth! For a small number of enthusiasts, increasing their number has a big effect on growth, the steep slope on the left of the graph.  However, the curve slows down; adding yet more enthusiasts has a less than proportional effect on church growth. Yes, it increases, but not in a large way.

Increase the Quality of Enthusiasts

Secondly, increase the effectiveness of the enthusiasts, whilst keeping the initial number of enthusiasts constant. In this case, each individual enthusiast is more “infectious”. The Christianity they have makes more impact on converting people; perhaps it is more challenging, more attractive. It is hard to be prescriptive. But the believer has something an unbeliever wants, so the unbeliever converts and becomes like it themselves. Figure 2 shows the effect of changing the quality of enthusiasts on church growth over 50 years. The “conversion potential” is a measure of enthusiast quality.

Graph: Change in church numbers by increasing quality of enthusiasts
Figure 2:  Effect on church growth of increasing the quality of enthusiasts

When enthusiast quality is low, the effect on church growth is moderate, shown by the straightish line on the left of the graph running from a conversion potential of 1 to just over 1.5. From a value of 2 onwards, church growth explodes. This value is near a “tipping point” so that even very small increases in the quality of enthusiasts has a massive effect on church growth. A conversion potential of 2 means each enthusiast could be used to convert two people if everyone they meet is an unbeliever.

Comparing Results

Comparing figures 1 and 2, it is clear that increasing the effectiveness of enthusiasts has a much bigger impact than just increasing their number, as long as they pass that effectiveness on. Quality is better than quantity. But how is the effectiveness of enthusiasts increased?

Churches prefer to increase the number of enthusiasts perhaps because they feel it is something they can handle. Invite more people to be trained to do evangelism, put on more courses etc. But to increase quality, that is the number of people an individual enthusiast could convert, requires a change both in believer and unbeliever. And only God can do the latter.

In reality, only God can change the believer as well. Yes, there are things churches can do to improve the effectiveness of those who witness. They can contact more people – the extra people contacted may already have their hearts ready to receive Christ. They can be better prepared to answer questions – just the sort of questions that might be stopping an unbeliever from coming to faith. But ultimately, just as it takes a work of the Holy Spirit to make unbelievers receptive, it also takes a work of the Holy Spirit to make a believer infectious – to make them a more effective enthusiast.


It is this work of the Holy Spirit that we are asking for when we pray for revival. This is why the church needs revival to see conversions increase and the church grow again. The trouble with praying for revival is that Christians are often more willing to pray for unbelievers to be open to Christ than they are for themselves to be set on fire and be made infectious Christians. Revival must start in the heart of the believer.

When, as Christian believers, we come to terms with the fact that the problem with church decline is in our hearts, and that the need for us to be effective in witness, to be infectious for God, will make huge demands on our lives – only then can our prayer for revival bring what we ask for. Because it is only that way, quality not quantity, that people will be able to say: “God did this, they could not have done this themselves.” It is quality, not quantity, that gives the glory to God alone. Conversions and church growth are only means to an end – that end is the glory of God, displayed in Christ Jesus saving sinners. “Lord Jesus, make us effective enthusiasts for You.”

References and Notes

[1] The limited enthusiasm model is described on my website

Limited Enthusiasm Model along with various results Principles of Revival Growth

The work is published:

A General Model of Church Growth and Decline. Journal of Mathematical Sociology, 29(3), 177-207, 2005.

A Dynamical Model of Church Growth and its Application to Contemporary Revivals. Review of Religious Research, 43(3),218-241, March 2002.

Mathematical Modeling of Church Growth, Journal of Mathematical Sociology. 23(4), 255-292, 1999.


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