The Greek word hilaterion has been one of the most disputed Pauline terms in the past century. Traditionally translate as “propitiation” or “propitiatory sacrifice,” many recent scholars have disputed the notion that Jesus died to appease an angry Father. In a 2000 article in the Tyndale Bulletin , Daniel P. Bailey observes that this debate has unfortunately shown precious little attention to the actual use of the term in the LXX or other Greek literature. The debate has been conducted not lexicographically or exegetically but theologically.
In Bailey’s doctoral research, summarized in the article, he found that hilasterion is always concrete, never referring to abstract ideas like propitiation or expiation. It never refers to the animal that would be killed in a sacrifice (though the related term hilasmos might). It mainly refers to of two things: either “durable votive offerings to the pagan deities” that are used to appease them, or the golden mercy seat on top of the ark of the covenant. In the first sense, the Trojan horse qualifies as a hilasterion.
In Romans 3:25, where Paul uses the term of Jesus, it refers instead to the mercy seat, the place of atoning sacrifice and not to the atoning sacrifice itself. Bailey suggests this reading of that text: “Paul focuses on ‘the law and the prophets’ and then more particularly on the Song of Moses in Exodus 15. The combination of God’s righteousness and redemption in Exodus 15:13 . . . closely parallels Romans 3:24 . . . . Furthermore, Exodus 15:17 promises that the exodus would lead to a new, ideal sanctuary established by God himself. God’s open setting out of Jesus as the new hilasterion - the centre of the sanctuary and focus of both the revelation of God (Ex. 25:22; Lv. 16:2; Nu. 7:89) and atonement for sin (Leviticus 16)—fulfils this tradition.”