If the command given by Jesus is to make disciples of all nations (or ethnic groups), then common sense would tell us our job is to find those nations (ethnic groups) that have not been discipled. People desiring to fulfill the Great Commission need to know where these “unreached” groups of people are, so that our efforts in completing the task will be productive.
WHY CLOSED CONTEXTS?
The vast majority of these unreached people live in an area of the world where traditional efforts will not meet the challenges of seeing those people reached with the Gospel of Jesus Christ. These are places where you can’t have a “religious” visa and where foreigners from non-profits are not readily accepted. The biggest reason these places still remain unengaged is the lack of Christians willing to think creatively to access these places.
Here is a video from Global Frontier Missions that gives a visual representation on the current state of the world and the task remaining.