Ubi Christus, ibi ecclesia, “Where Christ is, there is the church.” With this saying one of the oldest church fathers spoke of the mystery of the church. The saying also sums up Luther’s faith in the church. It is not the power of our faith, nor the holiness of our life that constitutes the church, but rather that “Where Christ is, there is the church.” When the church is called a holy people, a communion of saints, it is not to be understood in the way it has often been understood in the history of the church: “the church should be a holy people, therefore only the holy shall belong to her. Away with all the unholy! The honour of Christ demands it!” When the worst of sinners must be excluded from the fellowship, one must then begin to classify sins in order to determine which ones lead to exclusion. How often has not that been attempted, both in the past and more recently. How imposing was the strictness of the ancient church, when people sought to create a holy and pure church (as also happens now). Or consider the Donatists, who demanded that at least the clergy should be free of mortal sin. Whenever the attempt has been made to create an ideal church, the end result has always been bitter disappointment. The community of saints turns into a community of Pharisees.
— Hermann Sasse
(Brought to my attention by Rev. Paul T. McCain)