I've been wanting to write about Romans 3:25 for a year or two now, but I never got around to it. I think it actually contains an interesting nugget that strongly goes against Penal Substitution, so it's definitely worth exploring. What recently got my interest was that a Calvinist lady I was talking to online had kept bringing up Romans 3:25 and I just found out another Calvinist that often posts here has written up his own article on Romans 3:25 in support of Penal Substitution. So I take this as a sign that I need to talk about it too!
To quickly jump into it, in most translations Romans 3:24-25 says: "...through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood..." While there isn't anything particularly wrong with this rendering, the 'problem' is that this rendering unfortunately hides the fact that the Greek term for "propitiation" (hilasterion) here is actually a key term that has a unique usage in the Bible. It only appears twice in the New Testament, but the approximately 20 times it appears in the Old Testament, it particularly refers to the "Mercy Seat," which was the "Cover Lid" of the Ark of the Covenant (Ex 25:17-22; 31:7; 38:5-8; Lev 16:13-15). In fact the only other New Testament reference to hilasterion is Hebrews 9:5 (which contains an important detail about the Day of Atonement), explicitly speaking of the Mercy Seat. So it's most reasonable to say Paul is speaking of the Mercy Seat in Romans 3:25.
But how does this relate to propitiation, which is a term associated with turning away God's wrath? The way I understand it, Hebrew notion of "making atonement" derived from the term "to cover," roughly meaning to cover over an offense by making amends. This is not to be understood as throwing a rug over a dirty floor to hide the filth, but rather something like covering a wound with medication in order to heal the wound. Thus, they apparently connected that notion of "cover" with the "Cover Lid" (Mercy Seat) of the Ark of the Covenant.
The million dollar question to ask is: Did the Mercy Seat fit within the framework of Penal Substitution? If it did, then that would be a significant point in favor of the Protestant position, especially considering Romans 3:21-26 is one of the most important passages of the New Testament. On the flip side, if the Mercy Seat had nothing to do with Penal Substitution, then that's one more nail in the PSub coffin. The only way to really answer that is to see how the Old Testament spoke of the function of the Mercy Seat, which I'll now look at.
Michael (the Calvinist that I mentioned at the start of this article) makes the right connection here by concluding that Paul's mention of "Mercy Seat" in Romans 3:25 was calling to mind the Day of Atonement, since this is the central event where the Mercy Seat is employed. Michael also correctly notes that the Hebrew terms for Mercy Seat, atonement, ransom, redemption, purification, and expiation all stem from the same root-word, meaning they're all related on some level. To me, this alone provides a strong argument against PSub, since ransom/redemption and purification/expiation, along with atonement, never involve transferring punishment. For some reason, Michael doesn't make this connection and assumes Penal Substitution is a valid concept and writes his article as if PSub were a given rather than something to be proven. He even notes that the "redemption" of Romans 3:24 connects to the "propitiation" of Romans 3:25, which again is baffling as to how PSub can be derived from this.
Turning now to the Day of Atonement (which is described in Leviticus 16), it speaks of how the blood of the sacrificed animal was sprinkled on the Mercy Seat:
14 And he [the High Priest] shall take some of the blood of the bull and sprinkle it with his finger on the front of the mercy seat on the east side, and in front of the mercy seat he shall sprinkle some of the blood with his finger seven times. 15 Then he shall kill the goat of the sin offering that is for the people and bring its blood inside the veil and do with its blood as he did with the blood of the bull, sprinkling it over the mercy seat and in front of the mercy seat. 16 Thus he shall make atonement for the Holy Place, because of the uncleannesses of the people of Israel and because of their transgressions, all their sins. And so he shall do for the tent of meeting, which dwells with them in the midst of their uncleannesses.
So the emphasis here on the function of the Mercy Seat is making atonement for the Holy Place, indicating that this (and the Tent) were defiled by being in the presence of sinners. Since atonement is being made for objects, this can only mean making "atonement" on the Mercy Seat refers to cleansing/expiating, not punishing an innocent substitute. This is simlar to the Catholic notion of Satisfaction.
And later on Leviticus 16 continues:
30 For on this day shall atonement be made for you to cleanse you. You shall be clean before the Lord from all your sins. 31 It is a Sabbath of solemn rest to you, and you shall afflict yourselves; it is a statute forever. 32 And the priest who is anointed and consecrated as priest in his father's place shall make atonement, wearing the holy linen garments. 33 He shall make atonement for the holy sanctuary, and he shall make atonement for the tent of meeting and for the altar, and he shall make atonement for the priests and for all the people of the assembly.
This text clearly states the making atonement carries the (at least principal) function of cleansing/expiating, making these things worthy of being in God's presence. The notion of 'expiating' is not simply a cleansing, but solemnly removing all defiling filth. This is the main focus of the sprinkling of blood on the Mercy Seat. Indeed, Hebrews 13 really drives this point home:
11 For the bodies of those animals whose blood is brought into the holy places by the high priest as a sacrifice for sin are burned outside the camp. 12 So Jesus also suffered outside the gate in order to sanctify the people through his own blood.
This text is explicitly referring to the Day of Atonement (Lev 16:27), and the purpose of Jesus suffering in fulfillment of this is to "sanctify" people by His blood. This is the same cleansing/expiating function mentioned earlier. So atonement through the shedding blood is not to be understood as killing for the sake of transferring punishment, but rather for the sake of obtaining a 'cleansing detergent' of sorts. In other words, it's not the death that makes atonement, it's the blood that's taken from that animal that's sprinkled is what expiates/atones.
With this in mind, by using the term "Mercy Seat" in Romans 3:25, Paul was most certainly not suggesting the Cross involved Penal Substitution.