This Luther quote is printed in the Treasury of Daily Prayer, page 867, published by Concordia Publishing House, Saint Louis. It truly summarizes the grace of God found in Christ Jesus. I hope you enjoy it.
May you ever cherish and treasure this thought. Christ is made a servant of sin, yea, a bearer of sin, and the lowliest and most despised person. He destroys all sin by Himself and says: “I came not to be served but to serve” (Matthew 20:28). There is no greater bondage than that of sin; and there is no greater service than that displayed by the Son of God, who becomes servant of all, no matter how poor, wretched, or despised they may be, and bears their sins. It would be spectacular and amazing, prompting all the world to open ears and eyes, mouth and nose in uncomprehending wonderment, if some king’s son were to appear in a beggar’s home to nurse him in his illness, wash off his filth, and do everything else the beggar would have to do. Would this not be profound humility? Any spectator or any beneficiary of this honor would feel impelled to admit that he had seen or experienced something unusual and extraordinary, something magnificent. But what is a king or an emperor compared with the Son of God? Furthermore, what is a beggar’s filth or stench compared with the filth of sin which is ours by nature, stinking a hundred thousand times worse and looking infinitely more repulsive to God than any foul matter found in a hospital? And yet the love of the Son of God for us is of such magnitude that the greater the filth and stench of our sins, the more He befriends us, the more He cleanses us, relieving us of all our misery and the burden of all our sins and placing them upon His own back. All the holiness of the monks stinks in comparison with this service of Christ, the fact that the beloved Lamb, the great Man, yes, the Son of the Exalted Majesty, descends from heaven to serve me.