The model consists of three groups of people: unbelievers, enthusiasts (or active believers) who alone are responsible for spreading the faith, and inactive believers.
For simplicity all church members are assumed to be believers and vice versa. This is because there is no data on who among a church membership are true believers in Jesus Christ. It is difficult to see how such data could be reliably determined.
It is further assumed that members are identical with the attendees of the church. This is because there is only reliable data for attendance. Membership data is less reliable as different denominations and churches use different definitions of membership. Thus the model is dealing with attendance and recruitment issues only. Sometimes membership data needs to be used because no attendance data is available.
In reality there will be members and attendees who are not believers, members who do not attend and attendees who are not members. There may even be believers who are neither members or attendees. However these effects will tend to cancel each other out and the above assumptions imply that their net effect is negligible.
The dynamic hypotheses are:
Limited Enthusiasm Model
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. The enthusiasts are limited in their potential to convert as they cease to be enthusiasts after a given time. As such church growth is limited as enthusiasts fail to reproduce themselves from a shrinking pool of potential converts. Thus conversion falls below the loss of enthusiasts and church growth ceases with people left unconverted. 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.
The model predicts a threshold of revival-growth which depends on the size of the community that remains unconverted. If the potential for enthusiasts to reproduce themselves is over that threshold then rapid growth results. When the threshold drops to a lower level as people get converted, growth will slow and eventually cease.
|Conversion Through Enthusiasts (R)||Enthusiasts are responsible 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 many means.|
|Loss of Enthusiasm (B2)||After a period of time the enthusiasts lose their potential to convert. This slows and limits growth.|
|Diminishing Susceptible Pool (B1)||As 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 Enthusiasts||Not every convert becomes an enthusiast. Some become immediately inactive.|
Unbelievers convert to believers through contact with enthusiasts who have "spread the faith" to them. Some new converts become enthusiasts whereas some become inactive believers. Enthusiasts only remain active for a limited length of time before becoming inactive and taking no further part in spreading the faith.
The hypotheses can be expressed as a causal loop diagram, where the loops R, B1 and B2 represent feedback in the system dynamics model:
Growth is driven by the reinforcing loop R 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 thus church growth slows and eventually halts.
Spreading the faith means an unbeliever becoming a believer, a process called conversion. It is measured by the new convert becoming an attendee at church, or by becoming a member of a church. Thus if membership has increased or attendance has increased then the corresponding number of conversions are deemed to have occurred. In this model there is no other method of recruitment. Such as transfers from other churches or those born into the church.
Such conversion is usually accompanied by other observable changes in the convert such as enthusiasm for the Christian faith, adoption of a new moral code and resulting behavioral changes. Thus a believer is assumed to be easily distinguished from an unbeliever.
In this model it is assumed the faith is spread by word of mouth contact alone. The contact being between an enthusiast and an unbeliever through a network or friends, relatives, work colleagues and acquaintances. The enthusiast may be the person who "leads the unbeliever to Christ" as in saying a prayer of commitment in some evangelistic methods. It may be the person who explains the gospel to them. However it is more likely that the key contact is the person who invites the convert to a meeting, or church where the conversion occurs some time later at the hands of others.
The enthusiast is not necessarily a theological expert, or an evangelist, but a believer with enough enthusiasm to use their network of contacts to give people a positive attitude to Christ, Christian things or church. Something about them makes Christ attractive - attractive enough that the unbeliever may read something they would never have read otherwise, or go to a church meeting they would never have considered.
enthusiasts have been recruiting through their network of friends
and relatives which is now exhausted. There are three scenarios:
- The people in this network have become believers themselves;
- People in this network have become immune to any further pressure to join the church;
- The enthusiasts have ceased to have meaningful contact with unbelievers. Many new converts find after a year or so that they have a new set of friends in the church and their old unbelieving set have drifted away. Often the new convert does this subconsciously because being part of the church means taking on a new set of values leaving them uncomfortable with the values of their old friends. In strict churches they may even be encouraged to distance themselves from the world, inadvertently losing their recruitment potential.
- Churches do not just recruit or evangelise. After a while new converts find other work to do within the church and spend less time on recruitment activities.
- In periods of intense growth the pastoral demands of dealing with new converts prevent ministers from spending as much time on evangelism as they might like and thus their recruitment potential drops.
believers run out of enthusiasm for recruitment and settle into
a more subdued version of belief where the zeal to see new converts
has declined to the point of inactivity. Again there are a number
of scenarios behind this:
- The believer has forgotten why they converted from unbelief to belief. They now have no desire to see others converted;
- Often the believers gain status within the church and loses the real reasons why they joined in the first place. Any enthusiasm they now have is centred on their own advancement within the church;
- In non-strict churches the lifestyle is so close to the world that the new convert quickly sees little point in attempting to win people to the church. Believers are so similar to unbelievers that they have little to offer and so stop seeking converts;
- The believers may find the church so enjoyable that their enthusiasm is for their own experience of it, or of God, rather than to see others converted;
may be that the church has not lived up to expectation and the
believer has lost enthusiasm for anything to do with the beliefs.
Instead they have settled into a nominal church life.
Many of these reasons are summed up in Wesley's Law of the decay of pure religion. "Taking up the religion has produced benefits which makes missionary zeal too costly to engage in." (Kelley) (See Wesley's Law). Thus the assumption is that a believer's enthusiasm to recruit only last for a limited time after their conversion.
- They may be naturally shy and unwilling to engage in any form of recruitment;
- They may be a social isolate and have virtually no network of friends to influence;
- They may be a secondary convert, the spouse or child of a primary convert, who has"converted" for social reasons. Often such secondary converts have little real enthusiasm for the actual faith;
- It is possible for people to be converted to the ethos of the church - its services, customs, and morality - without ever being converted to the truth of the faith. As such they may have little desire to see others converted. Their "conversion" has been a purely social phenomena rather than one of deep religious conviction. Nevertheless they are part of the church, albeit an inactive believer.
As new converts are made the church grows and the unbelieving community gets proportionally less. This follows from an assumption called homogeneous mixing, meaning that an enthusiast is equally likely to have contact with an unbeliever or believer. Thus the chance of such a contact goes down as people are converted. If the majority of contacts come from intentional evangelism then this assumption will be invalid. However even when there is such evangelism most contacts come by word of mouth in day to day life. As churches are generally not ghettos but believers are equally represented in all areas of life then homogeneous mixing is generally valid.
The behaviour of the model is controlled by a number of parameters that reflect the church's effectiveness, and the response of society:
|Reproduction Potential||This 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 of the pool of unbelievers.|
|Duration of Enthusiastic Phase||The average length of time and enthusiast is active in conversion, before they become an inactive believer.|
|Fraction of Converts Enthusiast||The fraction of new converts who become enthusiasts. The remainder become inactive believers immediately on conversion.|
|Initial Fraction of Church Enthusiast||The fraction of the church that are enthusiasts at the start of the model.|
The results can only apply over short periods, up to about 15 years, as births and deaths are not included in the model. Thus the model is particularly suited to short intense periods of growth as is often seen during a revival.
The solutions exhibits the typical steep rise in the growth of the church, eventually slowing down well short of the whole community being converted. Such growth only occurs if the reproduction potential exceeds a threshold of revival-type growth which depends on the proportion of unbelievers in society only.
Thus it is a combination of internal reasons: effectiveness of enthusiasts, and external reason:, size of the community, that limits the growth of the church.