Paul understood that to be inwardly focused was to be outwardly blind. To be a missionary means meeting, learning and embracing those outside the family of God. Paul even likens it to becoming them; this was not a dry interpretation of an even dustier research project. This was a living, personal change based on wanting to see people become followers of Christ.
Follow the money trail, says the author, to see why a church exists. He has denominational language and examples, but is mostly spot on in terms of a church's outreach. Some saints have no idea why they were planted on this earth. Time to shake the tree!