What are the primary differences and implications of a propitiatory view of the atonement versus an expiatory view?

Given the massively fractured state of Christianity and the widely varied beliefs therein, a cross-denominational examination of soteriology could certainly yield strict, literal, and conflicting understandings of expiation and propitiation. However, I believe Roman Catholicism is a significant example wherein both concepts are used, amongst others, to assist in explaining a salvation plan that is ultimately mysterious. This shows that the concepts, though potentially antithetical by some strict understandings, are often used to present a balanced view of the mystery of salvation.

Consider that the online Bible of the United States Conference of Catholic Bishops renders Romans 3:25 as expiation.

²⁴ They are justified freely by his grace through the redemption in Christ Jesus, ²⁵ whom God set forth as an expiation, through faith, by his blood, to prove his righteousness because of the forgiveness of sins previously committed, ²⁶ through the forbearance of God—to prove his righteousness in the present time, that he might be righteous and justify the one who has faith in Jesus.

Also, consider the latest U.S. Catholic rendering of 1 John 2:2 is expiation:

¹ My children, I am writing this to you so that you may not commit sin. But if anyone does sin, we have an Advocate with the Father, Jesus Christ the righteous one. ² He is expiation for our sins, and not for our sins only but for those of the whole world.

But, when Pope Pius XII cites 1st John in paragaraph 73 of Mediator Dei, calling the Eucharist (the sacrifice of the cross made fully present again) expiation, propitiation, and reconciliation, the verse from 1st John is translated as propitiation.

The third end proposed is that of expiation, propitiation and reconciliation. Certainly, no one was better fitted to make satisfaction to Almighty God for all the sins of men than was Christ. Therefore, He desired to be immolated upon the cross "as a propitiation for our sins, not for ours only but also for those of the whole world"[67] and likewise He daily offers Himself upon our altars for our redemption, that we may be rescued from eternal damnation and admitted into the company of the elect. This He does, not for us only who are in this mortal life, but also "for all who rest in Christ, who have gone before us with the sign of faith and repose in the sleep of peace;"[68] for whether we live, or whether we die "still we are not separated from the one and only Christ."[69]

He further explains in paragraph 76 that Christ's sacrifice is "payment" for our sins, while at the same time calling it an "oblation" (a "gift" of thanksgiving), another potential for side-by-side antitheticals.

Now the Apostle of the Gentiles proclaims the copious plenitude and the perfection of the sacrifice of the cross, when he says that Christ by one oblation has perfected for ever them that are sanctified.[72] For the merits of this sacrifice, since they are altogether boundless and immeasurable, know no limits; for they are meant for all men of every time and place. This follows from the fact that in this sacrifice the God-Man is the priest and victim; that His immolation was entirely perfect, as was His obedience to the will of His eternal Father; and also that He suffered death as the Head of the human race: "See how we were bought: Christ hangs upon the cross, see at what a price He makes His purchase . . . He sheds His blood, He buys with His blood, He buys with the blood of the Spotless Lamb, He buys with the blood of God's only Son. He who buys is Christ; the price is His blood; the possession bought is the world."[73]

The General Instruction of the Mass calls the Eucharist, which is again the sacrifice of the cross made fully present again, propitiation amongst other things:

So, in the new Missal the rule of prayer (lex orandi) of the Church corresponds to her perennial rule of faith (lex credendi), by which we are truly taught that the sacrifice of his Cross and its sacramental renewal in the Mass, which Christ the Lord instituted at the Last Supper and commanded his Apostles to do in his memory, are one and the same, differing only in the manner of their offering; and as a result, that the Mass is at one and the same time a sacrifice of praise, thanksgiving, propitiation, and satisfaction.

And the Catechism of the Catholic Church speaks from multiple angles as well, first acknowledging that salvation is mysterious.

Jesus’ violent death was not the result of chance in an unfortunate coincidence of circumstances, but is part of the mystery of God’s plan, as St. Peter explains to the Jews of Jerusalem in his first sermon on Pentecost: “This Jesus [was] delivered up according to the definite plan and foreknowledge of God.”393 This Biblical language does not mean that those who handed him over were merely passive players in a scenario written in advance by God. (CCC 599)

It goes on, in implying that Christ's death was necessary to stave of "punishment", suggests a more propitiatory view.

Consequently, St. Peter can formulate the apostolic faith in the divine plan of salvation in this way: “You were ransomed from the futile ways inherited from your fathers... with the precious blood of Christ, like that of a lamb without blemish or spot. He was destined before the foundation of the world but was made manifest at the end of the times for your sake.” Man’s sins, following on original sin, are punishable by death. By sending his own Son in the form of a slave, in the form of a fallen humanity, on account of sin, God “made him to be sin who knew no sin, so that in him we might become the righteousness of God.” (CCC 602)

But, this is immediately followed by an explicitly labeling the cross as expiation. [1]

By giving up his own Son for our sins, God manifests that his plan for us is one of benevolent love, prior to any merit on our part: “In this is love, not that we loved God but that he loved us and sent his Son to be the expiation for our sins.” God “shows his love for us in that while we were yet sinners Christ died for us.” (CCC 604)

We could go on. Catholic literature and doctrine is filled with language describing the explaining the mystery of salvation. It's not all consistent. In some respects, each angle on salvation shows something that, if received literally or strictly, can feel ad odds with other angles. And in fact, there may very well be real conflict between the ideas.

It's probable that expiation and propitiation, as understood by some denominations, are incompatible salvation plans. But, in some traditions, such as Roman Catholicism, it's clear that both terms, as well as a variety of other language and "poetry", are used to explain salvation, which is first-and-foremost, a mystery. And, like the other major mysteries of Christian doctrine, the language surrounding it is not necessarily intended to be compatible.

In brief, the terms are both antithetical and complimentary, depending on how they're used and who's using them. There is clearly room for hard disagreement between the denominations. But, we also have at least one significant example wherein both terms are used to paint a fuller image of a single understanding of salvation.

_{[1]: It may also worth noting that the justice, wrath, and punishment of God's is uncertain language itself. Each of these must somehow be framed with respect to a God who is love. And with that perspective, propitiation and expiation may not be different things at all. It seems to be overtly and intentionally confusing and uncertain in any case.}

I can only answer from the Western bias as I fail to comprehend the Eastern thought even when it is explained. Western thought properly includes propitiation and expiation it does not toss one out for the other or put them at competing sides. It does not exclude either. However the Eastern thought seems to be uncomfortable with the propitiation involved in the cross and does not seem to me to believe that God’s wrath was poured out on the Son.

In Western thought propitiation, which is that part of the work of Christ on the cross, that makes ‘appeas*m*nt’ to an offended God, satisfying his wrath for sin. The other side of Western thought is expiation. Expiation occurs on the cross (not only to have the punishment of sin removed through propitiation) but to have sins cleansed and removed as well. Cleansing and deliverance from the actual power of sin is implied by expiation.

Cleary both of these aspects are implied by the scriptural view as the idea started with the Passover lamb and as well as the burned 'red heifer'. Both the concept of propitiation and expiation are clearly established under the Old Testament foreshadowing types. First, God’s ‘wrath’ in killing the first-born of Egypt was avoided by the Passover Lamb. The Jews were not cleansed by putting blood on the doorposts but were avoiding a deadly destruction of anger. Second, on the other hand, the burning of the 'red heifer' and collection of ashes oustide the camp clealry implies the actual ceremonial cleansing of the sacrfificial type. The ashes of the burnt animal were directly used for ceremonial washing buy mixing some ashes with water and sprinkling the unclean. (Ref Leviticus 19, Hebrews 19:13-14))

One can’t properly witness the ceremonial sacrifices of the Old Testament without believing both propitiation and expiation as inseparable objects, each meaningless without each other. First the worshipper or priest would lay hands on the animal to be sacrificed, symbolizing the transfer of guilt. Then the shedding of blood and total destruction of the animal would occur, symbolizing the appeas*m*nt to an offended God. Then the blood would ceremonially cleanse the worshipper. Clearly all these things support a proper view and cast grave doubts on any view that might try to limit them to only propitiation, or expiation.

Both propitiation and expiation are implied by each other in the removal of guilt. An angry God is no longer angry when guilt is transferred to another in propitiation. The stain of guilt is wiped away from expiation. Both propitiation and expiation are meaningless terms unless the removal of guilt in understood in each.

Both propitiation and expiation are implied by each other in the removal of guilt. An angry God is no longer angry when guilt is transferred to another in propitiation. The stain of guilt is wiped away from expiation. Both propitiation and expiation are meaningless terms unless the removal of guilt in understood in each.

The eastern view is that God changes when he ceases to be angry (according to the Western view) but propitiation does not imply any change in God whatsoever. He still is angry with sin but its guilt has been transferred to another. God can never change or remove his wrath. It must be extinguished on a a subject who bears the guilt of sin.