"God presented Him as a sacrifice of atonement..." (Rom. 3 v.25)
The word "atonement" means "reparation for a wrong". The word "propitiation", used in some translations, has a similar meaning: "the act of rendering favourable".
This tableau comes straight from Lev. Ch. 16. In this tableau, we see Moses' brother Aaron standing over two goats, one labelled "forgiven" and the other labelled "forgotten". One is to be sacrificed as a sin offering to atone for the sins and transgressions of the people, because Aaron knows that God will view the blood of the sin offering and have mercy on the people and forgive their sins. After the sacrifice of the first goat, Aaron then lays his hands on the second goat, to symbolically transfer the sins of the people to the goat. This goat then bears the blame for all the transgressions of the people and Aaron sets it free into the wilderness, where God will remember their sins no more. This goat is known as the "scapegoat" because it escapes into the wilderness, and, even though the scapegoat is entirely innocent, it has to carry the blame for the sins of others.
Jesus is like both goats - He died as a sacrifice for our sins, so that we could be forgiven, He carried the sins of the world, and He escaped death, as He was raised on the third day. And, as His body was taken from the cross and then laid in a tomb, Jesus carried our madness, our meanness, our evil, our stubbornness, our disobedience - all our sins - into the wilderness of the tomb, just as the scapegoat carried the sins of the people away into the wilderness of the desert. By carrying our sins far away, so that they can never return if we are repentant, they are forgotten by God - and Christ's blood is still cleansing us of sin, continually.