OK, fair enough. Here is my naive vision...
One gets saved.
One sits under elders for a number of years until you are a mature Christian. While you are sitting under those elders (5 fold ministry) you are taught your giftings and your ministry within the church.
Then you are given leave to go and minister in other places/assemblies where you are needed. You could go to a growing assembly, start your own, visit others depending where God leads.
I see in the original assembly as a nucleus of elders, babes and those still learning so you don't see people sitting on a pew for 40 years but going out and sowing into other places. You could grow into one of the elders in your original assembly or be used in another capacity in others.
Every saint has a ministry and it may not be exclusively needed in your local assembly. Sometimes just being there and worshipping with a group of people who need encouragement is a ministry. For example, a small assembly who has only a dozen people when you come from one that has 200 or more.
My theory is that the water is not moving is going to grow stagnant. We have little pools of swamp water where we should have large rivers flowing around to give encouragement and life to others.
It seems a little fearful to me to hold back the flow if we don't have any real good reasons not to.
OK, you can laugh now...
