For a very long time, many missiologists have tended to measure “progress in the Great Commission” (however that was defined) to some extent in the context of people groups, and how they are reached, evangelized and/or Christianized.

This thread has been pushed forward by the work of David Barrett, Patrick Johnstone and Ralph Winter, who each in his own way pushed thinking and activism related to unreached peoples.

“Reaching the unreached peoples,” in particular, has tended to replace the idea of “a church in every country” as the operative definition of closure or fulfillment of the Great Commission. Unreached People Groups better fit the Scriptural concepts of “every tribe, language, nation, tongue before the Throne” (Rev. 7:9).

The principal motivation behind the development of the unreached peoples concept was the idea of “gaps”—that there were languages and ethnic groups who had “no access” (defined as the reasonable access of individuals in the group to the gospel within their lifetime) principally being shared) or ethnicity (they couldn’t accept what was being shared by outsiders).

However, as we have refined our strategies for closure as “reach the unreached” strategies, two additional issues have emerged, and we’re struggling to address them.

The first is the danger of under-engagement. The principle is simple: we love lists, we want to check items off and so we did what is immediately required to put in a “good faith effort” to remove a people group from the list. We adopt a people group, mobilize a team, send them off to the group,and we remove this group from the “unreached” list.

This is exactly what would have to happen with a “sufficient” engagement, but it’s also what can happen with an “insufficient” engagement, and we don’t always take the time to ask whether an engagement is sufficient or not. A people group of 10 million, stretched over the geographic expanse of a country and spilling over into additional countries, will need more than a single team. To use an analogy, we can engage Moscow, while Vladivostok goes untouched within the lifetime of a single individual.

We may say “each missionary team can only do what it can,” and this is correct, but that represents only a tactical viewpoint. Strategy must think more broadly. If oneteam can only engage one major area within a people group, then multiple teams must be mobilized, and more rapidly.

The second issue, however, is my primary focus here: urbanization. At the turn of the 20th century, the world was just 14.4% urban—232 million out of 1.6 billion people on the planet. The majority of these urbanites (69%) were Christians because most of these cities were in Christianized countries. Just five megacities (population over one million) were majority non-Christian.

In a century, the situation has vastly changed. People moved into cities, driven by all sorts of motivations. Shortly past 2000, the world became majority urban. Today, about 56% of the global population lives in a city: 4.4 billion out of 7.8 billion.

Furthermore, as far back as the 1960s and 1970s, we began to see a shift in the religious composition of urbanites: there were more non-Christian city-dwellers than Christians, as cities developed in the non-Christian world. Today, just one-third of the world’s city dwellers are Christians. This doesn’t mean cities make people into non-Christians; it means that non-Christians urbanized into their own cities. Today the world includes more than 593 majority non-Christian megacities.

An example of this trend can be seen in China’s planned city clusters. They are planning to develop five regional cities, each with as many as 100 million people. In other words, there will be more people in these combined five cities than any other country in the world except India.

Cities present a specific challenge to the idea of “reaching Unreached People Groups”: they are huge mixing grounds. Some cities are more “rural” in character—various languages are segmented in mini-villages. Some cities are more “urban” in character—with lots of different people all mixed together, using broadly spoken trade languages to communicate on the job and in the markets. Whichever is the case, focusing on a city raises different strategic issues than focusing on a single people group or a language group largely spoken in a particular province or set of provinces. It brings the cross-cultural and cross-language dimensions of the task to bear in multiple ways earlier on. This means that including “cities” as segments to be listed, focused on, described, researched, documented, tracked, measured,and strategically engaged is probably just as important as “Unreached People Groups.”

We don’t want to lose the “unreached peoples” focus. But we must remember: the whole reason people have passionately advocated for the unreached is out of concern for gaps—collections of individuals who did not have gospel access. An exclusive focus on Unreached People Groups could, in fact, lead us to focus on, for example, Kazakhs, to the exclusion of very small groups (e.g., the thousand or so Avar in Kazakhstan) or diaspora groups int he same cities (e.g., Buryats).

Not every gap can be tracked at the global level. But global lists could continue to identify where gaps are potentially located. Different kinds of gaps can be found in cities than amongst unreached groups, and that means we need to give cities similar attention and effort.