Application of the Limited Enthusiasm Model with Reversion, Written in 2022.

The Elim Pentecostal Church in the UK is a protestant church founded in 1915 by George Jeffreys, a young Christian from Maesteg in South Wales. It was one of many churches inspired by the 1904-5 Welsh Revival, the Sunderland Conventions and the Pentecostal revival that started in Azusa St Los Angeles in 1906. It has grown continually since its inception. This analysis investigates how the church is experiencing revival growth and forecasts its potential future numbers.


Estimating Model Parameters

I will use Elim’s membership data to estimate the parameters of the Limited Enthusiasm Model with Reversion. Using this cut-down version of the Demographics Model avoids estimating values for child retention among church members, hardening rates etc. There is no information about these values for Elim. The reversion model has only five parameters:

  1. Reproduction Potential
  2. Duration Enthusiastic
  3. Loss Rate
  4. Fraction of Converts who Become Enthusiasts
  5. Initial Fraction of Enthusiasts in the Church

The key parameter is the reproduction potential. Its value will determine if Elim has revival growth.


Calibration Strategy

The best fit between data and model is found using least squares. To help find the most suitable parameter values, I vary parameters 3-5 above and optimise for 1-2, the reproduction potential and duration enthusiastic. Out of this optimisation set, I determined optimistic scenarios – those with moderate growth, and pessimistic scenarios – those with lower growth. I chose a representative of each optimisation close to the group’s average. Extreme values of parameters 3-5 were excluded even if they indicated high growth. I have chosen to be cautious.


Membership 2000–2020

I took the data from Brierley’s church statistics. I excluded his estimates for 2016-2019.

Every optimisation indicates that the Elim Pentecostal Church is experiencing revival growth with no sign of slowing down.

One such optimisation is given in figure 1. The reproduction potential chosen was an average of the optimistic scenarios, a value of 1.024. A typical pessimistic value is 1.003. The data fit in figure 1 is identical for both scenarios, which means I cannot choose between the scenarios on this data alone.

Figure 1: Data Fit for Elim Pentecostal Church Membership and the Limited Enthusiasm with Reversion Model

For both scenarios, the reproduction potentials are well above the revival threshold of 1.001 as of 2020. Thus, whatever data fit is used, Elim should continue to have revival growth for the foreseeable future, provided it keeps the same reproduction potential. “Revival growth” is where church and enthusiast numbers have accelerated growth.


Range of Optimised Parameters

The optimisations indicate a range of possible parameter values:

Reproduction Potential1.003-1.303
Duration Enthusiastic0.6-10 years
Loss Rate
(Reversion and Deaths)
2%–5%
Fraction of Converts who Become Enthusiastsabout 50%
Initial Fraction of Enthusiasts in the Church0.5%-10%
Model Parameters for Elim Pentecostal Church

Although there is a wide range of parameter values above, these do not affect the revival growth status of the church.


Future Projections

In Figure 3, I have extended the optimistic and pessimistic scenarios to the year 2100. Although these simulations are not predictions, the figure indicates possible futures, a range of forecasts, assuming the church reproduces enthusiasts in the same way. There is little to choose between the simulations up to the middle of the century. However, the pessimistic one slows down in the second half of the century. Even so, the church almost doubles in number.

Figure 3: Church Numbers for the Optimistic and Pessimistic Scenarios for Elim Pentecostal Church and Limited Enthusiasm Model

For the optimistic scenario, Elim’s growth is still accelerating at the end of the century. Consequently, the church would have increased five-fold over the century with the prospect of further growth. The optimistic scenario is more successful than the pessimistic one because the church has more enthusiasts and is better at reproducing them, figure 4.

Figure 4: Enthusiast Numbers for the Optimistic and Pessimistic Scenarios for Elim Pentecostal Church and Limited Enthusiasm Model

Long–Term View

The membership of the Elim church from 1920 to the present day shows continued growth with two periods of stagnation, figure 5. The fallback in the first of these periods, 1940-5, was undoubtedly affected by the war and possible the hostile opposition from other Christian groups that the early Pentecostal pioneers faced. The second failure to grow, 1970-80, is more intriguing. Perhaps people seeking the work of the Holy Spirit were attracted to the emerging Charismatic movement. Nevertheless, by 1990 Elim had caught them up. Indeed, I know from personal experience Elim congregations who learnt from churches in renewal, modernised their approach and seriously engaged with their communities.

Figure 5: Membership of Elim Pentecostal Church 1920-2020

So why has Elim sustained its growth from 1990 until now?

  1. Firstly, as I have already indicated, Elim were willing to learn from other successful churches outside their own denomination.
  2. Elim emphaised the need to make disciples, not just converts. Disciples who make disciples is a powerful driver of church growth.
  3. They are commited to growing churches and church planting. Elim have planted 58 churches in the last 20 years taking their total to 558 (2020).
  4. The church have remained commited to their core principles while being willing to modernise in the preparation.
  5. They still have something of the spirit of revival.
  6. I would like to think they still take baptism with the Holy Spirit seriously!

It would take further research to determine the causes behind Elim’s growth. However, it is clear that the denomination needs to continue its impressive church planting rate. There is plenty of room in the UK for more congregations!