Now God sees no sin in us. For in this heavenly righteousness, sin has no place. So now we may certainly think, "Although I still sin, I don't despair, because Christ lives--who is both my righteousness and my eternal life." In that righteousness I have no sin, no fear, no guilty conscience, no fear of death. I am indeed a sinner in this life of mine and in my own righteousness, but I have another life, another righteousness above this life, which is in Christ, the Son of God, who knows no sin or death, but is eternal righteousness and eternal life. For if the truth of being justified by Christ alone (not by our works) is lost, then all Christian truths are lost...On this truth and only on this truth the Church is built and has its being.
Martin Luther, Commentary on Galatians, Preface