Out of 230 countries in the world,55 are estimated to be less than 10% Christian, and their populations were 3.4 billion in 2000, and 3.8 billion in 2010.
Out of 3,812 provinces in the world, 978 are estimated to be less than 10% Christian.
Their populations sum to 2.8 billion people in 2000, and 3.5 billion people in 2010.
The average population of a province is 3.5 million.
The districts total 35.6 million square kilometers (population density 99/sq.km).
Note: there are 28 provinces estimated to be less than 2% Christian, and they have 729 million people.
Out of 16,542 people groups in the world (Joshua Project), 7,309 (44.2%) are estimated to be less than 10% Christian.
Their populations contain 4.3 billion people.
The average group size is 588,315.
The difference between the people group population and the district population suggests about a billion people who are part of <10% people groups are in districts that are more than 10% Christian.
Disclaimer: Dave Datema makes the point that all “cutoffs” measuring whether a segment is “reached or not” are fraught with danger.
I am not suggesting this as a “measure” of whether the task is finished.
I present these as simply a lens of a set of provinces with a specialized set of challenges to Gospel outreach.