I’ve written before about the importance of doubling time in movement speed. But the reality is: movements don’t “cleanly double.” Movement multiplication is messy: some people make disciples and many people don’t.Pareto’s Law, which shows up in most human endeavors, states that “for many events, roughly 80% of the effects come from 20% of the causes.” We see this in everything from economics to business to giving in church to the number of people who make evangelists. What might it look like in the growth of a movement? Below is a little theoretical spreadsheet. Starting with just 10 believers, we apply the 80/20 rule. Column 1 is the number of “iterations” (could be months or years). Column 2 is the number of believers. Column 3: 80% of those believers do nothing - they make no converts or disciples. Column 4: 20% make just 1 disciple. Column 5: 20% (of column 4, mind you) disciple a family (maybe their own; we average this to 3 believers). Column 6: 20% (of column 5) disciple multiple families (in this case, we estimate 4 (or 12 believers). Column 7 is the total number of new believers added by these 20% efforts (with the T columns showing the total believers from each of the 20% efforts).

Some takeaways:

- It is amazing what just 20% of a group can do! In 35 iterations, this movement would completely saturate a 100,000 population province. (Note that by iteration 27, they would certainly be noticed.) In 43 iterations, they could significantly impact a megacity (perhaps even saturate it). Although it would be ideal to have 100% cooperation, you do not have to have it. Normal human activity levels (80/20) would be sufficient.
- More important is how long each iteration takes. If each iteration requires a year before someone is “allowed” to make disciples, this chart would extend out very far indeed.
- neither of these charts take into account births or deaths (which generally only sustain a Christian community) nor immigration or emigration (which can dramatically impact small communities under oppression). The chart above shows that shepherding a small community through the critical early 19 iterations is vital.

A word of warning: a simple fluctuation in the % level can make a huge difference. What if a given church only has 10% making disciples, rather than 20%? Then we’d have a chart like the one below, representative (unfortunately) of a lot more churches. On the other hand, even a small fluctuation up can have dramatic results. If 25% are active, you would saturate a 100 million population in 43 iterations.