"Much weakness in evangelical mission work and mission churches is due to the fact that the missionaries have not been able or willing to make such cultural adaptation, social integration, psychological penetration, and spiritual identification as to make spiritual fellowship deep, lasting, contagious and vital. Somehow the wall of separation was not broken down. Isolationism developed or continued, and real effectiveness did not bless the work. There was no real communication or communion with the people he came to serve. The cultural worlds, though existing side by side, never really met and melted together. The missionary never 'sat where they sat,' though he sacrificed much and put forth great effort to communicate to them a message so precious to himself."
George W. Peters, A Biblical Theology of Missions (Chicago: Moody Press, 1972), p. 164.