Why rapid growth declines as movements increase in size

When they are small, movements tend to experience very rapid growth— they might double in size multiple times in a given year. Over time, as movements get larger, this growth tends to plateau. Why? Is it because, as time passes, evangelists get less enthusiastic? The case studies of movements I have collected don’t suggest this is the case. There’s a simpler and, I think, inevitable cause that actually hallmarks a success, not a failure.

Movements begin due to abundant Gospel-spreading activity.

Especially among the unreached, this activity is usually conducted by people with missionary or evangelistic giftings. Much of this activity could be termed “abundant sowing” (to use a Biblical term) or “super-spreading” (to use an epidemiological term that many have become familiar with). One example of this kind of event was the Day of Pentecost when Peter preached and saw 3,000 come to faith on that day. Other examples include Paul’s activities in various cities and places, where he evangelized large portions of the population in a relatively short period of time.

“Abundant sowing” is marked by large numbers of people being added through “conversion” growth. This growth can be explosively fast and can lead to rapid doublings and expansions of size. It can be exhilarating, especially if it happens in places where there has been no fruit for some time.

Movements continue to expand through the combination of two different kinds of growth: “abundant sowing” and “personal witness.”

The first Gospel-spreaders often (1) abundantly share the gospel, (2) make disciples, and (3) from this early harvest raise up additional new “super-spreaders”–people who are gifted apostles and evangelists, who almost immediately begin sharing widely and making disciples themselves. This cyclical process can lead to sustained multiplication that can bring a movement very rapidly to four generations and one thousand believers or more. (This process is outlined in the Heart and Four Fields).

As the movement grows, however, some portion of the growth will begin to come from “demographic” growth. Here I am referring to the everyday witness of the typical believer, especially to their discipling of family members. If you think about it, most believers don’t come to faith as a result of a missionary or passionate evangelist–they come to faith because of their parents, friends, or co-workers.

While all believers are commanded to be ready to share their faith, not all are gifted evangelists (just as not all are gifted pastors, or teachers, or prophets, or apostles). Further, passionate evangelists–“super-spreaders”–seem to be even rarer. DMM trainer David Watson once told me, “The person who shares the Gospel with 1,000 other people is pretty rare. Most people don’t do anything at all. The few who do typically just disciple their families.” Other DMM practitioners agree: of those trained in DMM principles, somewhere between 2 and 10% (more typically on the 2% side) actually do anything with the training.

So while it’s true that passionate evangelists find and activate other passionate evangelists, it seems there are only so many to find. Eventually, there are just far more parents and friends than there are super-spreading evangelists. Therefore:

  • In the early days, most growth in movements comes from 10s of evangelists who win 1,000s each, and also find other evangelists who do the same.
  • In later days, most growth in movements comes from 1,000s of households who win 10s each, and find other households who do the same.

Still, this is not the cause of the plateau. In fact, discipling activities from “typical” believers can lead to significant fruit and rapidly growing expansion (see this analysis).

The real decline in growth happens when a movement saturates a place or people group.

Any growth faster than a population’s overall growth will eventually run up against a hard barrier—the total size of the population they are working among. As more people in a place decide to follow Jesus, others—the remainder—will have made their decision not to follow. Places may not be majority-Christian, but they can still be majority-decided. Once this point is reached, the rate of growth will drop rapidly: the “ripe fruit” has already been harvested, and at best you are waiting for more fruit to ripen.

Reaching the plateau of saturation is not a failure—it is the inevitable result of successful, rapid multiplication.

Ephesus was an example of saturation: “This went on for two years, so that all the Jews and Greeks who lived in the province of Asia heard the word of the Lord.” (Acts 19:10). The Scripture doesn’t say they all believed, but it does say they’d all heard.

This plateau brings with it a new challenge. Once the area has been saturated with the gospel and future growth depends mostly on personal discipleship, we must ask: Are we done? Is this the end of the movement? If not, what’s next?

To reach this point, disciples have gotten good at making disciples, churches have gotten good at making churches, and leaders have gotten good at making leaders. To transition past this point, movements must now get good at making movements. They have learned how to “pass on what they know” (2 Timothy 2:2). They must now appoint people to be sent out for the sake of the Gospel (Acts 13:2). New growth must be sought by intentionally crossing borders. This will require movements to build the capacity to send its apostolic types to new, unsaturated places.

This is the same challenge everyone faces: will we choose to contribute to the completion of the Great Commission, or will we be content in our own little niche of the world? Everyone begins by focusing on their own “Judea and Samaria,” but eventually, if we are to obey Jesus completely, we must go to the uttermost parts of the earth. This is not just the domain of Western mission agencies—it is the natural next step to which movements, too, must aspire.

Is Islam growing faster than Christianity?

As in all things, it’s complicated.

Speed of growth is measured as the annual growth rate, which is expressed as a percentage.

At a global level, Islam is growing faster than Christianity: for the past several years (Status of Global Mission, linked on my Resources page) reports Islam is growing globally at about 1.87% p.a., while Christianity’s is growing globally at a rate of 1.3% and the population’s global AGR of 1.1%.

Both Christianity and Islam are growing faster than the world population (so the world is becoming more religious); Islam is growing faster than Christianity, so the % Muslim in the world is increasing.

However, the “fastest” AGR doesn’t equate to “the biggest religion.” Total Christians are significantly larger than total Muslims – 2.4 billion vs. 1.7 billion – and even by 2050, there will still be over a billion more Christians (3.4 billion) than Muslims (2.6 billion).

Further, while Islam has a higher growth rate globally, Christianity has a higher growth rate in most individual countries.

  • Islam’s growth rate is higher in 93 countries.
  • Christianity’s growth rate is higher in 137 countries. (I am here comparing the AGR as given in the last edition of Operation World).

Most of Islam’s increase comes from demographic growth (births) in high-birth-rate countries where Islam is the majority.

  • In countries where Christianity is the majority, the birth rate is lower (note–correlation, not causation).
  • In most places, the twin benefit of demographics and conversion gives Christianity the edge. (Very little of Islam’s growth rate comes from any kind of conversion: what conversion happens is nearly always in the context of marriage.)

A religion’s growth rate tends to ‘outstrip’ the competing religion when the ‘winner’ is small.

  • Smaller groups grow faster.
  • In 8 of the 10 countries where Islam has the highest % of the country, Christianity has the highest AGR.

However, in all of these ten countries (Sahara, Yemen, Morocco, Afghanistan, Mauritania, Somalia, Tunisia, Maldives, Comoros, Iran), the Christian population is a very tiny minority, and even with existing rapid growth rates it will not overtake Islam’s population any time soon.

Islam has the advantage in places where the birth rate is high, and some level of conflict or pressure leads to emigration of other religions. Examples include Niger, Djibouti, Turkey, Jordan, Turkmenistan, Iraq, Pakistan, Tajikistan, Kyrgyzstan, Qatar, Azerbaijan, Mali, Egypt, Uzbekistan.

In the largest populations of the world, it’s a mixed bag:

  • China – Christianity outstrips Islam, 2.7% to 0.3% AGR – and Christianity 8% (or more) vs Islam 2%
  • India – Christianity 3.7% vs Islam 2%, but Christianity is 6% vs Islam’s 14% of the population
  • USA – Islam faster (1.9% to 0.5%) but Islam is a tiny minority (1.6%). A growth rate of 1.9 will double the population in 37 years, from today’s roughly 5 million to ~2050’s 10 million.
  • Indonesia – Christianity faster, 1.6% to 1.2%, but Christianity small (16%)
  • Brazil – Islam faster, 4% to 1.1%, but Islam is just 0.29% of the country
  • Nigeria – Islam and Christianity are pretty much tied, 2.7% to 2.7%
  • Bangladesh – Christianity is faster, 3% to 1.5%, but Christianity tiny (1% of country)
  • Russia – Islam faster (0.9% vs Christianity nil growth), but note that evangelical Christianity is growing at 2.3% (although it’s a small portion)
  • Japan – Islam growing at 1.3%, Christianity shrinking at -0.2%, and Christianity makes up 2% while Islam makes up 0.15%. Both tiny slices.
  • Mexico – nil growth for Islam vs 1% p.a. for Christianity.

So when someone says Islam is the fastest religion growing in the world, the answer is “Yes, but…” Don’t leap to the conclusion that Islam is the winner in terms of adherents. Christianity is larger in numbers globally, growing fastest where Islam is strongest, and certainly “in competition” in the largest populations.