Propitiation, as we saw in Chapter 5, addresses the wrath of God. It is the work of Christ saving us from God’s wrath by absorbing it in His own person as our substitute. 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.
Bridges finishes the chapter in this way:
The work of Christ in finished. Nothing more remains to be done. God's wrath has been propitiated. Our sins have been removed. The question is, will we appreciate it, not only for our initial moment of salvation, but for our day-to-day acceptance with God? It is only as we do the latter that we will truly begin to appreciate the glory of the cross and the unsearchable riches of Christ.