In a sermon on John 1:29, Martin Luther said this about the unsurpassable love of Christ at the cross:
It would be spectacular and amazing, prompting all the world to open its 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 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. For how amazing it is that the Son of God becomes my servant, that He humbles Himself so, that He cumbers Himself with my misery and sin. . . . He says to me: “You are no longer a sinner, but I am. I am your substitute. You have not sinned, but I have. The entire world is in sin. However, you are not in sin; but I am. All your sins are to rest on Me and not on you.”
No one can comprehend this. In yonder life our eyes will feast forever on this love of God.