The call to the cloister demanded of Luther the complete surrender of his life. But God shattered all his hopes. He showed him through the Scriptures that the following of Christ is not the achievement or merit of a select few, but the divine command to all Christians without distinction. Monasticism had transformed the humble work of discipleship into the meritorious activity of the saints, and the self-renunciation of discipleship into the flagrant spiritual self-assertion of the "religious."

translated as The Cost of Discipleship (1959), p. 47. - Discipleship (1937) - Costly Grace