John 1:29-31 — The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world.
This is He of whom I said, After me cometh a man which is preferred before me: for He was before me.
And I knew Him not: but that He should be made manifest to Israel, therefore am I come baptizing with water.
John knew of the prophecies of Jesus as Lamb. He was oppressed, and He was afflicted, yet He opened not his mouth: He is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so He openeth not his mouth (Isaiah 53:7).
taketh away = take up, bear
taketh away sin (singular) — Christ's cross-work, but also the ultimate removal of sin and its consequences in the new Heaven and new Earth. And He said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely (Revelation 21:6).
This is He — John reminds his listeners of what he said the day before.
In the other gospels, John announced Jesus as a lion — but that's His second (kingdom) coming.This time, He came as a lamb.
I did not know Him — Probably John hadn't seen Jesus before this, but even if he had, he didn't know Him as Messiah until he saw the Spirit like a dove.
John came and baptized to make Israel aware of Christ's coming, to prepare them.
- sinless — But with the precious blood of Christ, as of a lamb without blemish and without spot (1 Peter 1:19)
- willing (led) — He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened He not His mouth (Acts 8:32).
- sacrifice — For then must He often have suffered since the foundation of the world: but now once in the end of the world hath He appeared to put away sin by the sacrifice of Himself (Hebrews 9:26).