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Church Growth Modelling

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What is Church Growth?

"Church Growth" is the discipline that seeks to analyse why Christian churches, at various levels of organisation, grow or decline, both numerically and spiritually. Numerical growth can include attendance at worship, membership and the number of congregations. Spiritual growth is harder to quantify, but is an important part of the subject.

Church growth thinking can be divided into three strands:

  • The Church Strand, which is based within Christian denominations and exists to serve their needs. It is based on theological principles, organisational pragmatism, and ideas that originated in the church growth movement of the 20th century. Principles are disseminated in popular books, training courses and seminaries.
  • The Social Science Strand, whose focus is primarily academic research and is part of the sociology of religion. Hypotheses are tested with statistical methods and results published in peer-reviewed academic journals.
  • The Sociophysics Strand, which uses mathematics, physics and computer simulation. Techniques are drawn from population modelling, statistical mechanics, system dynamics and differential calculus, with the consequences of hypotheses analysed within the strict rules of mathematics. Sociophysics models are published in peer-reviewed academic journals.

There is some overlap between the three strands. Church Growth Modelling is within the sociophysics strand, but uses elements of the other two.

Church Strand of Church Growth

The Church Growth Movement of the second half of the 20th century was the primary means through which many churches came to embrace church growth principles. The movement is deemed to have originated with Donald McGavran, a missionary to India who through his research on the mission field became the a specialist church growth educator (Pointer 1984, p.14). Indeed it is he who coined the expression "church growth" as he felt "evangelism" and "missions" had lost their true meaning, and with it some of the burning zeal of the church to see the great commission fulfilled (Pointer 1984, p.19). McGavran's first book on his work, Bridges of God published in 1955, is regards as the start of the church growth movement (Pointer 1984, p.14).

McGavran' research was conducted while he was on the mission field from 1923 to 1954 with the help of Methodist bishop, J. Waskom Pickett. Between them they analysed data from the growing churches within India, attempting to understand the best way to conduct missions from the point of view of seeing people converted. This was far from being an academic study, souls were at stake, nevertheless the work was of a high academic calibre. Although results were published from the 1930s onwards little interest was generated until 1955 with the appearance on Bridges of God (Pointer 1984, pp.13-14).

Now in the USA, McGavran went on to publish the booklet How Churches Grow in 1959, in order to challenge missionary organisations to become more effective. Meanwhile he was conducting research from missions in other countries to support his principles. In 1961 he founded the Institute of Church Growth in Oregon to train students to be in effective mission. The institute proved popular, especially with international students, and quickly grew out of its premises. In 1965 McGavran was able to move the institute to the Fuller Theological Seminary in Pasadena, where he became founding dean of the School of World Missions. To this day Fuller has been hugely influential in the field of church growth, and has seen a number of well known church leaders and church growth experts on the staff, including J. Edwin Orr, John Wimber, Peter Wagoner and Eddie Gibbs (Pointer 1984, pp.14-15).

McGavran's most influential, and comprehensive, book is Understanding Church Growth (1970), which has remained in print ever since. It is here he discusses at length the homogenous unit; a group of people who share a number of common characteristics, such as language or race. He noted that congregations and denominations grew within such units. His book also covers aspects of revival and the relationship between healing and church growth.

Church growth ideas have been propagated by many books since McGavran. In the UK I Believe in Church Growth (Gibbs 1975) and How Do Churches Grow(Pointer 1984) have been influential in churches. These were less research-based than McGavran, but had considerable practical help for the average church pastor. For example, Pointer gives guidelines on how to measure congregational growth and procedures to help plan for growth. Although these principles could be applied to any organisation of people, religious or not, it was welcome common sense for churches that had never had to think this way before.

A slightly different approach was pursued by Win Arn, a graduate from Fuller who founded the American Institute for Church Growth, subsequently Church Growth inc, now Arn (1985) developed the stages of the congregational lifecycle, paralleling the lifecycle effects in many organisations not just churches (Adizes 1992). The ideas have been used by Glenn Davies, an Australian bishop, and presented in a very readable form by McIntosh (2009).

Church growth ideas have also been promoted by societies. For example the British Church Growth Association was formed in 1981, gathering together researchers, consultants, teachers and practitioners (Pointer 1984, p.18). It influenced both churches and seminaries and eventually ended in the early part of 21st century. This date perhaps marks the end of church growth as a movement, however it had succeeding in persuading many denominations to adopt its principles and their seminaries to teach church growth courses. (I did a such a course in 1990 as part of the extension studies programme at St John's College Nottingham.)

Church growth theories require good data. In the UK excellent data has been provided by Peter Brierley, first of Marc Europe, then Christian Research, now independent, who has compiled denominational statistics as well as conducing comprehensive surveys. In the USA there is the American Religious Data Archive, with providing worldwide data. Many denominations publish their own statistics.

Social Science Strand of Church Growth

Sociology of religion is a large subject dating back to Max Weber and before. Within it there is a significant thread that seeks to understand religious growth and especially decline. Perhaps the oldest theory is Secularisation, which attempts to explain religious decline in terms of modernisation and rationalism, which causes religious institutions to lose their power. The subsequent decline in the influence of religion on society results in numerical church decline. The theory is found in the writings of Marx, Weber and Durkheim, to name but a few (Davie 2007).

The comments of the anthropologist Wallace (1966, p.265) are typical of the secularisation hypothesis: the evolutionary future of religion is extinction, as are Berger's remarks that assertions of supernaturalism would be restricted to smaller groups or backward regions (Berger, 1970). However secularisation can also be viewed as a process that tames sects in churches. Although this may lead to their demise, secularisation is only one of a number of processes which include those of reaffiliation, revival and sect formation, often in a later generation. (Stark & Bainbridge 1985, Ch. 19). As such churches may become extinct, but religion does not.

Although religion has declined in the West there has been notable areas of growth, especially among conservative churches in the USA in the latter part of the 20th century. This has led to many challenges to the secularisation hypothesis. In particular in 1972 Kelley published a controversial book Why Conservative Churches are Growing, comparing and contrasting the growing evangelical and conservative churches of the USA with the declining, largely liberal, ones. He developed a hypothesis that growth was linked to strictness, i.e. strict churches are strong hence are more likely to grow (Kelley 1972). This came to be know as "Kelley's thesis", and led to a flourish of research to either prove or disprove this thesis (Hoge & Roozen, 1979; Roozen & Hadaway, 1993).

Numerous authors have noted that in the USA the Christian churches, as well as other religions, continue to grow despite the predictions of secularisation theory. This has led to the beginnings of a paradigm shift in thinking from secularisation theory, as typified by Berger (1969) , towards one which sees religions flourishing in what is essentially an open market religious economy. This fundamental change is described by Warner (1993), and is typified by the work of Stark (Stark, 1996; Stark and Bainbridge, 1985; 1987; Fink and Stark 1992) and Iannaccone (Iannaccone, 1992; 1994; Iannaccone, Olson, and Stark, 1995), among others. Indeed Iannaccone, using a model based on rational choice theory, affirms Kelley's thesis that strictness, makes churches strong, even in modern society. This has implications for the study of church growth as it becomes increasingly accepted that religious revivals are not only facts of history, but continue to take place in modern society among all classes (Stark & Bainbridge, 1985, ch.9; Stark & Iannaccone, 1994; Warner, 1993, pp.1046-1048).

Attempts have been made to reformulate secularisation theory into the neo-secularisation thesis (Yamane 1997, Sommerville 1998, Gorski & Altinordu 2008). One leading proponent of the neo-secularisation approach (Chaves 1994) has argued that secularisation does not refer to religious attendance or religious affiliation but to religious authority. If religious authority, understood as religion's influence over society's beliefs, thoughts and behaviours has declined in any way then "secularisation" has taken place. This would certainly reflect late 20th and early 21st century USA , despite the growth of conservative churches.

From a system dynamics point of view it is not a question of which theory is correct: secularisation, new paradigm or neo-secularisation. Each of these contain competing force. Which forces dominate at any time would determine which theory, or none, approximates to the truth.

Sociophysics Strand of Church Growth

Sociophysics is a name given to a broad range of mathematical modelling techniques used in the social and economic sciences, based on theories similar to those in physics. They include statistical mechanics, agent-based models and population modelling, but are not necessarily limited to these techniques. It is more a way of thinking that perceives a model as a part of a more general theory within a social system. Such models are highly mathematical and are capable of quantitative testing and predication. Many of the models are dynamic, predicting changes over time, and providing quantitative explanations of behaviour. Such theories are often called social diffusion. Within the subject there are models of the spread of religion and church growth.

It is perhaps Lionel Penrose (1952) who could be credited with the first model of church growth, as he applied his idea of “mental” epidemiology to outbreaks of religious enthusiasm. However as the work was not quantitative it is difficult to verify his conclusions. A more quantitative attempt at church growth modelling, using ideas from gas dynamics, was proposed by Logan & Dye (1984), but the approach was not pursued further. In 1999 Hayward proposed what has come to be known as the Limited Enthusiasm model, a population model explaining the growth of the church using the differential equations for the spread of a disease. The theory was applied to religious revival (Hayward 1999, 2002). It was extended for general church growth and decline (Hayward 2005) and applied to a range of Christian denominations. It has also been re-expressed using the system dynamics methodology (Hayward 2000, 2002, 2014), extended to include renewal (internal revival) (Hayward 2010) and applied to Islam in the UK (Hayward et al, 2015). Other applications and models of church growth are on this website.

Others from the physics community have attempt models of the growth of religion. Ormerod & Roach (2004) used scale free networks to model the spread of heresies in history. Ausloos & Petroni (2007, 2009, 2010) and Ausloos(2012) have used ideas from statistical physics and population modelling. A more general model of ideological competition, which includes religion, was constructed Vitanov, Dimitrova, & Ausloos (2011) using differential equation modelling, following a generalised Verhulst law. More recent models have proposed theories of church growth where the main agents of growth are not the most recent converts, generalising the concept of enthusiast (Ochoche & Gweryina, 2013; McCartney & Glass, 2014; Madubueze & Nwaokolo 2014).

Apart from the models on the Church Growth Modelling website, there are few examples of church growth built with system dynamics. Gaynor, Morrow & Georgiou (1991) modelled the sustainability of a religious order, but the growth of the organisation was not linked to the behaviour of individuals. Likewise (Bullock 1999) applied system dynamics to the analysis of parish growth; here the major emphasis was the financial management of the parish, rather than its growth mechanism. Acuña Moreno et al (2001) constructing a microworld applied to a South American Christian denomination.

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Church Growth Modelling