Do you have sheep like this in your flock? They come to church and feed with the other sheep, we guard them and make sure they stay healthy, but the church never gets any benefit from them. They are three-bags-full sheep, but the church never gets any wool. All their time, all their energy, all their talent is being given to someone else. Those sheep are part of your flock but they are sheep you cannot shear.
Seymour, D. B. (2006). Sheep You Cannot Shear. Journal of the American Society for Church Growth, 17(2), 3-7. Retrieved from https://digitalarchives.apu.edu/jascg/vol17/iss2/2