Results of the Limited Enthusiasm Model with Demographics

Secularisation is the process where religion loses its significance and influence in society (Religion Media Centre). This effect is represented in the Demographics model by open unbelievers and believers becoming hardened unbelievers. This model uses the limited enthusiasm principle to describe conversion.

There are two losses from the church. Some believers leave each year, and a fraction of their children do not embrace the Christian faith. These leavers may remain open to reconversion, or they become hardened. This latter effect represents ex-believers who hold some resentment toward the church. Each year, a fraction of these become open to conversion again. However, secularisation is the reverse effect: the hardening of once-open unbelievers.

Secularisation represents changes in society outside the church. Such changes may be influenced by the behaviour of those in the church. It could also be caused by the rise of anti-Christian ideologies among unbelievers. Despite occurring outside society, secularisation worsens church decline by shrinking the pool of those open to conversion.

Consider two types of secularisation, generational and intentional.

Generational Secularisation

Generational secularisation occurs when the children of those open to Christianity become hardened, drifting away from the stance of their parents. This effect can happen with open unbelievers who still identify with Christian culture. They may have been brought up in church themselves but no longer attend or take their family. Their children, the next generation, move further from the culture. Eventually, there is a generation for which Christianity is alien and uncomfortable, something they cannot identify with.

Figure 1 compares an equilibrium run with no secularisation (EQ low CP run) with one where 50% of the children of unbelievers become hardened (black dashed line). The conversion rate is low, and initially the church makes up only 20% of society in equilibrium. Nevertheless, no open unbelievers become hardened. However, with 50% of their children secularising, open believers fall in numbers. It follows that the number in church drops and stabilises to less than 10% of society. Generational secularisation has a profound effect on church decline.

There is a further reduction in church numbers if half the reverts become hardened (dotted curve, figure 1). Another reduction happens if half of the believers’ children become unbelievers and half of those hard (green dashed curve). The drop is slight as the church is much smaller than the unbelieving society.

The major effect on stable church numbers is among unbelievers, the part of the population undergoing secularisation. The conversion rate is sensitive to society’s openness to the gospel. In most cases, the church is a minority in society. Thus, societal changes – the environmental context – greatly influence church dynamics. However, that influence is very long-term. In Figure 1, it takes over 500 years to stabilise. Plenty of time for the church to take remedial action!

Intentional Secularisation

Intentional secularisation occurs when open unbelievers choose to become hardened to Christianity. Perhaps they had been church members, left the church, and now become anti-Christian. Maybe they join another religion or become humanists. Perhaps they had never been Christians but had accepted Christian values without much thought. Now they are rejecting those values.

In Figure 2, the equilibrium run is the horizontal line at 11%, corresponding to a hardening rate of 1%. Reduce the hardening to 0.5% (solid brown curve), and the church grows and stabilises at a higher value, 14%. Increasing the hardening rate increases secularisation, and church numbers drop. Doubling the hardening rate to 2% reduces the number to 4.5% of the population. A 3% hardening rate means the church will become extinct in 200 years.

Secularisation strongly affects the church’s ability to grow or to combat its decline. In this sense, it is correct to say secularisation causes church decline. Although not in this model, the church itself may cause secularisation by its actions. Indeed, churches that are successful at conversion may cause hostility among unbelievers. This effect needs additions to the model!

Church Growth in a Secular Culture

Figure 3 illustrates a growing church in three cultures of differing hardness. The blue line is a church growing in a population where 30% of the initial population are hard (solid blue line). Early growth is slow (top graph), but church numbers approach equilibrium in 50 years. The rise in enthusiasts (bottom graph) shows a significant revival over 25 years, followed by a significant drop afterwards. Much of the church’s success was achieved in those first few decades.

If the unbelieving population had been all open, a completely non-secular culture, church growth would be much faster than the 30% hardened run (red dashed curve, top graph). There is also considerable overshoot after 25 years. There is a similar overshoot among enthusiasts in the bottom graph. The more open society sees a faster and larger revival, but the final equilibrium remains the same. This result is demographic, due to reversion and reconversion.

By contrast, church growth in a completely hardened society is more difficult (black, dotted line). There is a 70-year period where church numbers are close to zero (top graph). Also, there is a shorter period where enthusiast numbers are close to zero (bottom graph). With random fluctuations, there is a high chance of extinction during those periods. If the church does pull through, the same equilibrium as the other runs is achieved. The time to reach equilibrium is over a century as the demographic effects of an initial fully-hardened population work through.