Lexicon

G2434 - hilasmos

Strong's: G2434 · BLB lookup Pronunciation: hil-as-mos' Part of speech: masculine noun Root: from hilaskomai (G2433), "to be propitiated / become favorable / show mercy" NT occurrences: 2 (both in 1 John, 2:2 and 4:10) LXX equivalent: renders Hebrew kippur / kippurim (Leviticus 25:9; Numbers 5:8), the Day of Atonement vocabulary; also used for forgiveness / propitiation contexts.

Semantic range (Thayer / BDAG / TDNT)

An appeasing, propitiating, the act of turning away wrath
The means of appeasing / a propitiation, the offering / sacrifice that effects propitiation
Expiation, the removal / cleansing of sin (the related sense, contested)

The KJV: "propitiation" (both occurrences). NIV / NRSV use "atoning sacrifice" to capture both senses. NASB95: "propitiation."

The propitiation / expiation debate

The translation of hilasmos / hilastērion / hilaskomai has been one of the most contested issues in 20th-century NT theology:

Propitiation, the act of appeasing wrath. The wrath is real, personal, divine; the sacrifice turns it away. Object of action: God Himself (His wrath is propitiated).
Expiation, the act of cleansing / removing sin. There is no divine wrath to appease; the sacrifice merely removes the moral stain. Object of action: sin (it is expiated).

The dispute:

C. H. Dodd (The Bible and the Greeks, 1935), argued that hilaskomai in Hellenistic Jewish Greek (esp. LXX) does not carry the pagan-Greek "appease an angry god" sense. The biblical concept, Dodd argued, is expiation, God Himself provides the means of dealing with sin. Dodd's reading was influential in the RSV translation tradition.
Leon Morris (The Apostolic Preaching of the Cross, 1955; The Atonement: Its Meaning and Significance, 1983), comprehensively refuted Dodd, demonstrating that:

The propitiation / wrath-appeasement sense is preserved in LXX usage despite Dodd's claims
The OT sacrificial system itself presupposes divine wrath (Numbers 16:46-48; Psalm 78:38)
NT hilasmos / hilastērion contexts (Romans 3:25; Hebrews 2:17; 1 John 2:2; 4:10) align with the broader NT theology of divine wrath against sin
Removing propitiation makes the cross unintelligible, what is being accomplished if there is no wrath to deal with?

Modern Reformed consensus (D. A. Carson, John Stott, Wayne Grudem, J. I. Packer "What Did the Cross Achieve?" 1973), sides with Morris. Both propitiation and expiation are present, but propitiation is primary; expiation is consequent. Christ's sacrifice propitiates the Father's wrath and thereby expiates the sinner's guilt.

The contested issue is not whether expiation occurs but whether the wrath-appeasement aspect is preserved. The Reformed position: yes, decisively.

Hilasmos in Johannine theology

Both NT occurrences are in 1 John:

"He Himself is the propitiation (hilasmos) for our sins; and not for ours only, but also for those of the whole world." (1 John 2:2, NASB95)

"In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation (hilasmos) for our sins." (1 John 4:10, NASB95)

The two passages establish:

Christ Himself is the propitiation, not just brings propitiation; is it. The personal-substitutionary force is direct.
Propitiation has universal scope (1 John 2:2), "for the whole world" (peri holou tou kosmou). The Calvinist / Arminian dispute over the extent of the atonement engages this verse extensively.
Propitiation is grounded in the Father's love (1 John 4:10), the Father is not the object of the Son's persuasion against the Father's wrath; rather the Father Himself sends the Son to be the propitiation. This refutes the simplistic caricature of "angry Father / loving Son", the Father's love initiates the propitiation; the Son executes it; the Spirit applies it.

Hilasmos and the Trinitarian shape of atonement

The Trinitarian structure of the atonement is exhibited in the hilasmos texts:

The Father sends the Son out of love (1 John 4:9-10; John 3:16)
The Son is the propitiation, freely offering Himself (Hebrews 9:14, 26; 10:10)
The Spirit applies the propitiation to believers (Hebrews 9:14, "the eternal Spirit"; Romans 8:11; Titus 3:5)

The cross is therefore not God's wrath vs God's love but God's wrath and God's love working together through the Trinitarian persons, the Father's love providing what the Father's righteous-wrath demands.

Patristic / scholarly note

The patristic tradition uniformly affirmed propitiation / wrath-appeasement, though it was not always foregrounded in their atonement theology (which often emphasized recapitulation, ransom-from-Satan, or theosis). Athanasius (De Incarnatione 7-9), Cyril of Alexandria, Augustine all engage hilasmos in atonement contexts.

The Reformation reset: Luther (Bondage of the Will; Galatians commentary); Calvin (Institutes II.16-17, extensive treatment of propitiation and atonement), both develop substitutionary-atonement / propitiation as central. The Reformed confessions (Heidelberg Catechism Q.37-44; Westminster Confession 8.5) canonicalize the doctrine.

The 20th-century controversy: Dodd (The Bible and the Greeks, 1935, the demythologization-friendly position); Vincent Taylor (Jesus and His Sacrifice, 1937, sympathetic to Dodd); Leon Morris (The Apostolic Preaching of the Cross, 1955; The Atonement, 1983, the decisive Reformed counter); J. I. Packer ("What Did the Cross Achieve?", 1973, the popular-level Reformed defense); D. A. Carson (The Difficult Doctrine of the Love of God, 2000) on integrating wrath and love.

Modern conservative scholarship: Stephen Travis (Christ and the Judgement of God, 1986); Thomas Schreiner (The King in His Beauty, 2013; New Testament Theology, 2008); Steve Jeffery, Mike Ovey, Andrew Sach (Pierced for Our Transgressions, 2007), defending penal substitutionary atonement comprehensively.

Relation to hilastērion and lytron

The hilasmos family of words connects to:

G2435 - hilasterion, the means / place of propitiation; the kapporet (mercy seat) of the OT atonement system; applied to Christ in Romans 3:25.
G3083 - lytron, the ransom / price paid for release; the substitutionary-payment dimension; applied to Christ in Mark 10:45 and 1 Timothy 2:6.
G0629 - apolytrosis, the act of redemption / deliverance achieved by ransom; the result of the lytron-payment.

The four words combine to form the NT atonement vocabulary cluster: Christ as lytron (price), as hilastērion (means / place of propitiation), accomplishing hilasmos (the propitiation itself), resulting in apolytrōsis (redemption / deliverance).

Notable verses

Hilasmos-family in NT

1 John 2:2; 4:10, hilasmos, Christ as propitiation
Romans 3:25, hilastērion, Christ as the place / means of propitiation
Hebrews 2:17, hilaskesthai (verb), Christ as merciful high priest making propitiation
Luke 18:13, hilasthēti moi, "be merciful / propitious to me, the sinner" (the publican's prayer)

OT background

Leviticus 16, Day of Atonement; the kapporet / mercy seat
Leviticus 17:11, "the life of the flesh is in the blood, and I have given it to you on the altar to make atonement"
Numbers 5:8, hilasmou in LXX, propitiation

Notes

Lexical workspace for hilasmos.