All churches want to grow. It is part of the mission of the church to spread the faith, to make converts, to see new people come to Christ. For that mission to be fulfilled, congregations become larger or new congregations get planted. Thus, growth is a legitimate expectation of any church.

However, it is the experience of many growing churches that the larger they get, the harder it becomes to maintain that growth. There is a limit to church growth, especially in a congregation. These limits are barriers that stop a church from growing indefinitely and hinder its attempts to fulfil the commission that Christ gave.

There are many reasons why church growth is limited, and there may be more than one present in any given church. Whatever the reasons, each one will require the church to do something to remove the barrier so that growth can continue. It is not a sin to plateau. But failing to remove an obvious limit that causes the plateau is an issue. God does not expect us to sit back and let things happen. He gives instructions, e.g. “Go into all the world and preach the gospel to every creature” Mark 16:15. Christians are not passive in church growth!

This blog, one of a series, explores two simple limits to church growth using the system dynamics methodology. The two limits are connected with supply and demand. The church supplies religion, society demands it.

Limit 1: Lack of Supply

If a church relies on new people coming to church by their own choice and puts no effort into seeking new people, then it will eventually stop growing. It is assumed that there is some demand for religion in society, but the church does nothing to meet people and supply what they are looking for. Instead, it relies on people searching the church out.

Assuming there is a constant number of new people coming to church every year, i.e. demand for religion remains constant, why then does the church stop growing? The answer is that growth is not the only process taking place – people are also leaving. Some people move for jobs; some people fall away. Others, of course, die. These cause the growth to be limited.

Figure 1: Constant Demand Model of Church Growth

A simple system dynamics model will illustrate this effect, figure 1. The stock, Church, measures how many people belong to the church. The inflow, come to church, is the fixed number who come to church each year, presumably because they are seeking the Christian religion. Assume it is 5 people per year.

The outflow, leave church, represents the people who leave each year. It is not constant but depends on the number in the church. The connector from church to leave church indicates this. The reasons people leave are personal, i.e. individual. Thus, if there is an average chance of someone leaving, then the more people, the more will leave. So assume a fixed percentage leave every year, say 5%. This effect is indicated by the feedback loop B in figure 1, where B means balancing. The bigger the church, the more people leave, thus the less in church. Changes in the church feed back on itself and, in this case, oppose growth.

Figure 2 shows what happens to a church of 60 people. It grows over the following 50 years, but the growth slows because as it gets bigger, the number of people who leave is larger, figure 3. It will stop growing at 100 people because 5% of 100 is 5; the outflow matches the inflow!

Figure 2: Limit to Church Growth Caused by Constant Demand and Rising Number Leaving
Figure 3: Demand, “come to church”, Matches Leaving at the Limit

It is like driving a car and taking your foot off the accelerator. The car comes to a halt, slowing down through air resistance and friction. The situation with the church is the same; the “force” due to people leaving slows church growth down until it stops.

To remove the barrier the church could reduce the losses, but with death and geographical mobility among the reasons for leaving then there is only so much that can be done here. The key to dealing with the limit cause by lack of supply is to do something to increase recruitment. The principle must be the bigger the church, the bigger the effort in recruitment. More people in the community are met, thus greater sharing of the gospel, more persuasion. Don’t take demand for religion for granted.

From a system dynamics point of view the balancing feedback loop B needs opposing. Somehow a form of feedback that reinforces growth must be introduced.

Limit 2 Lack of Demand

Assume that the church supplies religion to the population according to its size. In plain English, the larger the church, the more people go into the community advertising the faith, actively finding those who demand religion, “seeking and saving the lost”, Luke 19:10. This is indicated by the feedback loop R in figure 4. It is a “force” exerted by the church on those outside, causing some to join. It is called R for reinforcing. The bigger the church, the more join – growth accelerates. The supply rate is the percentage of the church who recruit one person each year, given there is sufficient demand. Let the supply rate be 8%.

Figure 4: Supply and Demand Model of Church Growth

However there is not a constant demand for religion. Society is finite, and the number outside the church is a limited pool on which to draw, the stock Outside Church, figure 4. Instead, any demand for religion is a fixed percentage, demand rate, because as the pool of those outside goes down, less people will remain who demand church. Let the demand rate be 0.5%. Thus there is another force opposing growth, the loop B1.

Assume that those outside the church are 2000 and the leaving rate stays the same, now called loop B2 and still opposing growth. Thus a church that starts with 50 people (2.4% of society), grows initially, figure 5, as demand exceeds supply, figure 6. There are plenty of people demanding religion outside the church, more than the church can recruit each year, thus the church’s supply, R, controls the growth.

Figure 5: Limit to Church Growth Caused by Failure to Increase Demand

However, at some point, supply exceeds demand, figure 6. As hard as the church tries, there are no longer sufficient people demanding religion for them to find in the random pool of people they contact each year. Now demand, B1, controls the growth and eventually equals the leaving rate where growth stops, around 160 in this case, about 7.8% of society.

Figure 6: Demand Eventually Falls Below Supply, Limiting Growth

Incidentally, if those who leave the church are not open to rejoining, then the church will transition to decline. Only if some ex-members are recycled can the church keep its numbers steady.  

To remove the barrier it must first be noticed there is a serious flaw in one  of the model assumptions above. “Seeking and saving the lost” does not refer to only gathering in those who demand religion, those open to becoming Christian, those interested in church. The “lost” in that gospel passage means everyone, and seeking and saving them means persuading everyone to accept Christ, even if they are disinterested or hostile. It is convincing them that they should demand the religion even if they don’t at present.

Thus, to remove this barrier, the church should be creating demand; not just advertising the faith, but witnessing their faith – doing things that cause people to change their mind. Church members must have a quality of life that makes others want the same. It can be evangelism, ministries of compassion and mercy, whatever – as long as those outside the church realise they are missing something they don’t have, never thought of having or even hated, and that church is the place they find it. The demand rate cannot be left constant; it is the church’s job to increase it.

The next blog on limits to church growth will explore how the church may influence the demand, and the further barriers to growth these uncover.  Limits to Church Growth – Part 2.


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