“The Reformation set free the question and nature of the church from the question of who belongs to it. This was a decisive stage. Roman Catholicism and the pre-Reformation church had thought that the question of the nature of the church would be answered by a definition of its extent. The Reformation, and particularly the Lutheran concept, first says what the church is and leaves the question of its boundaries open.
It’s first concern is not the unveiling of the divine mystery of who belongs to the church, and who does not, the question of election and rejection, it is not aimed first and foremost at judging and distinguishing people; the most important thing is that the manifest saving act of God, the present Christ, his Word and sacrament, should be seen and adored. There are no theoretical statements about the saved and the lost, there is no verdict “This person belongs to the church, this person does not,” but simply the joyful cry of those who have been granted a share in a great, astonishing gift, “Here is the gospel!” “Here are the pure sacraments!” “Here is the church!” “Come here!”
…So Christianity and the Reformation did nothing more at this point than to cry confidently one after the other “Here is the church!” “The true church of JEsus Christ!” This cry is one of humility and thankfulness. It is not boasting, but praise of God.”
…Yet the outcome of the Reformation was the victory, not of Luther’s perception of grace in all its purity and costliness, but of the vigilant religious instinct of people for the place where grace is to be obtained at the cheapest price. All that was needed was a subtle and almost imperceptible change of emphasis, and the damage was done. Luther had taught that we cannot stand before God, however religious our works and ways may be, because at bottom we are always our own interests. In the depth of his misery, Luther had grasped by faith the free and unconditional forgiveness of all his sins. That experience taught him that this grace had cost him his very life, and must continue to cost him the same price day by day. So far from dispensing him from discipleship, this grace only made him a more earnest disciple.”
Dietrich Bonhoeffer in A Testament to Freedom, p.159-160 and 309