I believe that John the baptist was refering to the sacrifice because it was a jewish tradition to sacrifice a lamb for the coverage of sin, and In This passage He was saying, "Look, the lamb of God, who takes away the sin of the world".
The concept was radical because now it was saying that He was the sacrifice for the whole world, not only the jewish people.
It really touched my heart the fact that God the father was himself offering the sacrifice (giving a solution) to help solve this terrible problem in humantiy (sin). It was not the man who invented the concept of doing it right, but God himself because He was looking to end the abyssm of separation between Holiness and sinfulness.
He is a problem solver, not a problem seeker!!!
Thank you Lord for your merciful Love.