From the Word
29 The next day he saw Jesus coming toward him, and said, “Behold, the Lamb of God, who takes away the sin of the world! 30 This is he of whom I said, ‘After me comes a man who ranks before me, for he was before me.’ 31 I myself did not know him; but for this I came baptizing with water, that he might be revealed to Israel.” 32 And John bore witness, “I saw the Spirit descend as a dove from heaven, and it remained on him. 33 I myself did not know him; but he who sent me to baptize with water said to me, ‘He on whom you see the Spirit descend and remain, this is he who baptizes with the Holy Spirit.’ 34 And I have seen and have borne witness that this is the Son of God.”
John 1:29–34, RSV
By this John means to say: I have, by my teaching, made you all sinners, having condemned your works and told you to despair of yourselves. But in order that you may not also despair of God, I will show you how to get rid of your sins and obtain salvation. Not that you can strip off your sins or make yourselves pious through your works; another man is needed for this; nor can I do it, I can point him out, however. It is Jesus Christ, the Lamb of God. He, he, and no one else in heaven or on earth, takes our sins upon himself. You yourselves could not pay for the very smallest of your sins. He alone must take upon himself not alone your sins, but the sins of the world, and not some sins, but all the sins of the world, be they great or small, many or few.
Now if you are able to believe that this voice of John speaks the truth, and if you are able to follow his finger and recognize the Lamb of God carrying your sins, then you have gained the victory, then you are a Christian, a master of sin, death, hell and all things. Then your conscience will rejoice and become heartily fond of this gentle Lamb of God. Then you will love, praise and give thanks to our heavenly Father for his infinite wealth of mercy, preached by John and given in Christ. Finally you will become cheerful and willing to do his divine will, as best you can, with all your strength. What lovelier and more comforting message can be heard than that our sins are not ours any more, that they no more lie on us, but on the Lamb of God. Lying on him, sin must be vanquished and made to nothing, and likewise death and hell, being the reward of sin, must be vanquished also. Behold what God our Father has given us in Christ.
Take heed lest you presume to get rid of the smallest of your sins through your own merit before God, and lest you rob Christ, the Lamb of God, of his credit. John indeed demands that each one should know himself, repent and grow better, yet not in himself, but in Jesus Christ alone.
Martin Luther and John Sander, Devotional Readings from Luther’s Works for Every Day of the Year (Rock Island, IL: Augustana Book Concern, 1915), 451–452.