Church growth research has changed into a slightly disreputable branch of missiology. Originally it focused on the growth of God’s church in non-Christian settings. The American incarnation of the discipline quickly shifted its focus to the growth of ‘my church’.  Though there certainly is a place for that kind of thinking, three important disadvantages were often connected to this new approach. Firstly, church growth evolved into marketing and biblically sound theology was put on the back-burner if it was perceived as hindering the quick growth of the church. Churches turned their Jesus into a more palatable, less demanding god and in the process lost their voice of calling people to repentance and faith. Secondly,

the emphasis of growing ‘my church’ without much reflection on where the members are coming from, contributed to the ‘recycling of the saints’ without growth of God’s Kingdom. Thirdly, putting up the megachurches as examples for others to aspire to, resulted in a lack of recognition for the strategic value of church multiplication (even though some of the megachurches are also exemplary in planting daughter churches).

As a consequence, church growth research fell out of favour in a large part of the missiological world. Yet there is no reason why this should be so. If it true that Jesus Christ is the hope of this world, and if it true that church membership is an indicator (not a sufficient but yet a necessary indicator) of a connection with him, church growth research remains important. What kind of people become Christians? What kind of churches attract non-believers? The answers to these questions may help inform policy decisions by churches and missionary organizations. To be acceptable to Christian leaders, the above mentioned tendencies need to be addressed. We believe that our conversion research project on the growth of the Thai Protestant church did just that.

Thai research project
In the Thai research project (in which a lot of churches and organizations played a role) all 4,000 Thai Protestant churches were approached with questions about membership and attendance, so that a reliable count of Thai Protestants was achieved. Thailand has only 0.5% affiliated Protestant Christians, which is lower than the numbers given by Operation World and the World Christian Encyclopedia. Yet the news is not all bad. Protestants are growing 4% faster than the population. This means that Thai Protestantism is on the same growth curve as the church in the first three centuries AD. Christianity grew from a small group in Israel to the large majority in the Roman Empire. If the Thai church keeps growing at the present rate and the Lord tarries, Thailand will be fully Christian in 135 years.

Not satisfied with just counting, we wanted to gain deeper insight into the composition and growth of the ethnic Thai church. In a random sample of 94 ethnic Thai churches all worshippers were asked to fill in a one page questionnaire. The next step was very important. Instead of looking at just local church growth, the research focused on conversion church growth. A conversion growth rate for each church was calculated based on the percentage of respondents who had become Christians in that church within the last decade. After analyzing the data from 94 churches and over 3000 respondents from all over Thailand and from all kinds of Protestant traditions, we were able to give clear answers to the questions ‘What kind of people become Christians?’ and ‘What kind of churches attract non-believers?’

What kind of people become Christians?
In the mission world, there are some popular ideas about who is receptive to the Gospel. Some of these ideas proved to be true, some others totally erroneous. As all over the world, in Thailand traditional religionists are far more receptive to the Gospel than adherents of the majority religion (Buddhism in Thailand). Women are more receptive than men, migrants more receptive than non-migrants, and students more receptive than non-students. In none of these cases however, the less receptive group was more than two times less likely to become Christian. So though some real differences in receptivity were found, in none of these cases there either was a mass-movement toward Christ or total resistance. Contrary to conventional wisdom, in Thailand is youth not more receptive to the Gospel than older people. People over 60 years of age are even twice as likely to become Christians as youth in the age 15 -19.

Other findings were more ambivalent. In Thailand, urbanites and high-educated people are more likely to become Christians than rural people and low-educated people. However, there was no indication that they were more receptive to the gospel. The reason for this pattern in all likelihood is that churches and missionary organizations focus on reaching high-educated urbanites more than low-educated rural people.

Several other interesting findings all point toward the paramount importance of personal relationships in the conversion process. Probably the most staggering statistic from the research project is that a Thai with a Christian relative is 700 times more likely to become a Christian than a Thai without a Christian relative. Of course this has to do with opportunity. Many Thai people who do not have a Christian relative have never had the chance to respond to the Gospel. Yet more than anything else, it shows that the Gospel travels along relational (above all family) lines. The same conclusion can be drawn from the fact that 70% of all converts say that a lay church member, so not a pastor or missionary, was the main influence in their conversion. Because of a popular formalized ‘accepting Jesus’ ceremony normally led by a pastor, the real number is probably even higher than that.

Another finding that stresses the importance of social networks in conversion is that people in a village with a church are 100 times more likely to become Christians than people in a village without a church. The very committed are willing to travel to church. But for the large majority of the population Christianity only becomes an option when there is a church within their community. This gives strong support to the goal of saturation church planting.

A final ‘nugget’ from the data reinforcing the importance of personal relationships was a surprise to the researchers. Limited to one choice, 60% of all converts claimed that printed media had played a role in their conversion, while only 10% mentioned non-printed media (30% said media did not have any influence). The likely explanation for this phenomenon is that radio and television are literally broadcast media, but printed media are used in personal relationships. Even the oft-maligned tracts were mentioned almost twice as often as radio and television combined!

What kind of churches attract non-believers?
The discussion about what kind of churches grow through conversion can be an emotional one, and is not often burdened with a lot of factual information. For this research project 59 claims were analyzed statistically. 14 were clearly correlated with conversion growth. When these 14 variables were entered into a mathematical model only 4 were left that together predict over 90% of the conversion growth of an ethnic Thai church.

Two major factors tell most of what you need to know about the conversion growth potential of a Thai church. The first one is the age of a church. Age predicts about 60% of the conversion growth. Younger churches attract many more converts than older churches. (E.g.: a 5 year old church attracts 6 times more converts than a 75 year old church with for the rest the same characteristics.) The second important factor is traditionalism. Churches with a lot of extra-biblical rules and an emphasis on position instead of spiritual giftedness are growing much slower than non-traditional churches. Traditionalism predicts another 20% of the conversion growth of a church.

Two minor factors add some extra understanding. 8% of conversion growth is predicted by whether or not a church is charismatic (charismatic churches grow faster), and 5% by whether there are women in the church board (churches without women in the board grow faster).
While the two minor factors are theological questions that should be decided on their own merits and not on the question of effectiveness, the two main factors should be theologically uncontroversial. Therefore they clearly point into a ministry direction. Many churches, new churches, and churches that do not limit member ministry by emphasizing church rules and church positions are the way that God uses to build his Kingdom in Thailand.

Why this is important
Hopefully by now it has become clear that conversion research is a useful tool to analyze the state of a national or regional church. Because it focuses on conversions rather than membership growth, a church that plants daughter churches is as likely to have a high conversion growth rate as a megachurch that incorporates everybody into one church. Taking the network of daughter churches into account as well, the conversion growth rate is likely to be even higher, because of the higher growth rate of younger churches.

Getting your growth from the membership of other churches is not going to result in a higher conversion growth rate. So the conversion growth rate used in this research project is a better measure of a church’s contribution to the advance of the Christian faith than traditional church growth measures. In most cases the analysis will point to practices that facilitate conversions and practices that build barriers against conversion.
On an individual level, conversion research is likely to pinpoint receptive segments of the population, or, equally important, show that segments that are perceived as receptive in fact are not more receptive but only more heavily targeted than other groups. Again this analysis likely results in common-sense ministry recommendations.

How I can help you
This article is written in the hope that in many more countries and regions research like this will be done to serve God’s church. I am aware that few missionaries are equipped to the advanced analyses used in the research project described here. However, there are several resources available that make conversion research do-able for missionaries with a research interest but minimal statistical training.

1.    A full description of the research process and findings can be found in Marten Visser,  Conversion Growth of Protestant Churches in Thailand, published by Boekencentrum.
2.    I am happy to provide a CD-ROM with
     a.    Example forms and questionnaires  
     b.    A check-list for conversion research projects
     c.    An example data set from the Thai research project
3.    I am available for consultation on new conversion research projects.
4.    Turnkey statistical analyses are being worked on. The researcher only needs to key in the data, and the analyses will be performed automatically.

I hope and expect that conversion research will bring new life to the use of statistics in missiology, and that it will help God’s Church in many countries to understand what is going on, and how the churches may best use the opportunities God gives them.

This article was first published in Evangelical Missions Quarterly, april 2010.