“Now I should like to know whether your soul, tired of its own righteousness, is learning to be revived by and to trust in the righteousness of Christ. . . . My dear brother, learn Christ and him crucified. Learn to pray to him and, despairing of yourself, say, ‘You, Lord Jesus, are my righteousness, but I am your sin. You have taken upon yourself what is mine and have given to me what is yours. You have taken upon yourself what you were not and have given to me what I was not.’ Beware of aspiring to such purity that you will not wish to be looked upon as a sinner, or to be one. For Christ dwells only in sinners. On this account he descended from heaven, where he dwelt among the righteous, to dwell among sinners. Meditate on this love of his and you will see his sweet consolation.”
Martin Luther, writing to George Spenlein, quoted in Theodore G. Tappert, editor, Luther: Letters of Spiritual Counsel (Philadelphia, 1955), page 110. Language updated.