What the Gospel IS: Expiation-the removal of sin
“As far as the east is from the west, so far does he remove our transgressions from us.”
Expiation, which basically means “removal,” accompanies propitiation and speaks of the work of Christ in removing or putting away our sin. Such is the symbolism of the two goats used on the Day of Atonement. The first goat represented Christ’s work of propitiation as it was killed and its blood sprinkled on the mercy seat. The second goat represented Christ’s work of expiation in removing or blotting out the sins that were against us. The object of propitiation is the wrath of God. The object of expiation is the sin, which must be removed from His presence.
The Gospel for Real Life by Jerry Bridges