Now I should like to know whether your soul, tired of it’s own righteousness, is learning to be revived by and to trust in the righteousness of Christ.  For in our age the temptation to presumption besets many, especially those who try with all their might to be just and good without knowing the righteousness of God which is most bountifully and freely given us in Christ. They try to do good of themselves in order that they might stand before God clothed in their own virtues and merits.  But this is impossible…Therefore, my dear brother, learn Christ and Him crucified. Learn to pray to him and, despairing of yourself, say, “Thou, Lord Jesus, art my righteousness, but I am thy sin.  Thou hast taken upon thyself what is mine and hast given to me what is thine.  Thou have taken upon thyself what thou wast not and hast given to me what I was not.” … For why was it necessary for him to die if we can obtain a good conscience by our own works and afflictions?  Accordingly you will find peace only in him and only when you despair of yourself and your own works.  Besides, you will learn from him that just as he has recieved you, so he has made your sins his own and made his righteouness yours.

– Martin Luther (From a letter to George Spenlein)
1483 – 1546