This post covers this concept and may be updated from time to time to improve it for clarity and answer questions. We use terms to quantify the "remaining task" - words like "unreached," "unevangelized," "unengaged," and "least-reached."
Often we use these words interchangeably. This can be quite dangerous, as they do not mean the same thing, and we may not be meaning the same thing when we use them. An in-depth look at the history of these terms and how they have been used is given in the book World Christian Trends. Here, I'm just going to briefly summarize how they are used today.
"Unreached" is a term that was originally defined in a meeting of missiologists held in Chicago shortly after the whole idea of unreached peoples really took off. It was defined as, "a people group lacking a church that can evangelize the group to its borders without cross-cultural assistance."
- It is not a statement about how many people in the group are Christians, or even how many have heard the Gospel.
- "Unreached" is a measure of the local church's ability to finish the job on its own.
- As originally defined, there was no statistical measure that quantified this. It wasn't "2% Christian" or "5% Christian"--it was far more a subjective evaluation of the local church.
- This "squishiness of definition" leaves significant flexibility: a church that could not have evangelized a large group in the 1970s might be able to do so now, thanks to the multiplying power of media, the Internet, etc.
"Unevangelized" as it is generally used was defined in the World Christian Encyclopedia (and World Christian Trends, its related work) as a mathematical equation for estimating the number of people within a people group that would have access to the Gospel at least once in their life time.
"Unevangelized" is used by others with slightly different definitions, so it's important to understand what is meant by "unevangelized" whenever it is used. Usually, when people refer to "2.3 billion unevangelized," they are referring to the number in the Status of Global Mission, which comes out of the World Christian Encyclopedia research.
- It is based in part on how many people are Christians, and in part on the results of various ministries (like Bible distribution, film, media, personal witnessing, mass crusades and the like) aimed at the group.
- It IS a quantification of the number of people who have access to the Gospel. A group can be, for example, 30% evangelized, which means that many people have heard the Gospel (and 70% have not).
- It is not a statement about the quality of the local church or its ability to finish the task on its own.
"Unengaged" was created by Finishing the Task and is defined as a people group lacking a team with a church planting strategy. If a group of several million has a team of 2 or 3 that has "engaged it" with a church planting strategy, then it is "engaged" (but it may be "underserved" based on a ratio of 1 team per 50,000). The unengaged list is maintained by Finishing the Task and is a derivative of other lists.
"Least-reached" is a generic term used to refer to the core of the remaining task. It does not have a specific definition, and is often used when no specific definition is desired. The number of people considered "unreached" and those considered "unevangelized" are often different, because the definitions are different:
- a group can be reached yet mostly unevangelized, particularly if the church within the group is sufficiently large and strong (even if it is a minority).
- a group generally will not be evangelized and unreached.
- People will disagree about whether certain traditions within the Church are 'reached' or even 'evangelized.' For example, some have argued that you are not adequately 'evangelized' unless you are a Christian, and even that some within the Church are 'unevangelized' because they do not know the Gospel (they are 'cultural Christians'). Unevangelized does not usually measure whether a person knows or can share the Gospel; it measures whether they have access to it.