Churchly Quality Control VIII: A word on church discipline
When a church comes to the place where it can no longer exert discipline, then with tears before the Lord we must consider a second step. If the battle for doctrinal purity is lost, we must understand that there is a second step to take in regard to the practice of the principle of the purity of the visible church. It may be necessary for true Christians to leave the visible organization with which they have been associated. But note well: if we must leave our church, it should always be with tears . . .
from The Church Before the Watching World