### Core Meaning & Semantic Range
The Greek noun μοιχεία (moicheía, `{{G3430}}`) derives from the verb μοιχεύω (moicheuō, `{{G3431}}`), meaning "to commit adultery." At its core, μοιχεία refers to the act of sexual infidelity committed by a married person with someone other than their spouse. It specifically denotes the violation of the marriage covenant through illicit sexual intercourse. The term carries a strong connotation of treachery and betrayal, as it breaks the exclusive bond and vows established within marriage. While its primary semantic range is literal, describing a physical act, biblical usage, particularly in prophetic literature and the New Testament, extends its meaning metaphorically to encompass spiritual unfaithfulness or idolatry, depicting a people's betrayal of their covenant relationship with God.
### Biblical Occurrences & Contextual Analysis
The term μοιχεία appears in several key New Testament passages, consistently highlighting its gravity:
* In [[Matthew 15:19]] and [[Mark 7:21]], Jesus lists μοιχεία among other grievous sins that "come out of the heart." This emphasizes that the sin of adultery is not merely an outward act but originates from internal desires and intentions, underscoring the spiritual depth of sin.
* The narrative in [[John 8:3]] famously depicts the scribes and Pharisees bringing a woman "caught in adultery" to Jesus. Here, μοιχεία refers to the literal act, serving as the basis for a legal and moral challenge to Jesus, revealing societal attitudes and Jesus' transformative approach to sin and judgment.
* Paul includes μοιχεία in his list of "works of the flesh" in [[Galatians 5:19]], contrasting it with the "fruit of the Spirit." This placement signifies that adultery is a manifestation of fallen human nature, antithetical to a life led by the Holy Spirit.
* The author of Hebrews issues a stern warning in [[Hebrews 13:4]]: "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge." This verse unequivocally condemns adultery, upholding the sanctity of the marital bond and affirming divine judgment against those who defile it.
* Significantly, in [[Revelation 2:22]], μοιχεία is used in a metaphorical sense concerning the church in Thyatira. Here, it refers to spiritual unfaithfulness, likely involving idolatrous practices and compromise with pagan worship, depicting a betrayal of Christ akin to marital infidelity. This usage underscores the profound theological implications of spiritual deviation from God.
### Related Words & Concepts
The study of μοιχεία (moicheía, `{{G3430}}`) is enriched by examining its linguistic and conceptual relatives:
* **μοιχάω (moichaō, `{{G3429}}`), μοιχεύω (moicheuō, `{{G3431}}`):** These are the verbal forms, meaning "to commit adultery." They describe the act itself.
* **μοιχός (moichos, `{{G3432}}`):** The masculine noun for "adulterer."
* **μοιχαλίς (moichalis, `{{G3428}}`):** The feminine noun for "adulteress," often used metaphorically in the New Testament to describe a spiritually unfaithful generation ([[Matthew 12:39]], [[James 4:4]]).
* **πορνεία (porneia, `{{G4202}}`):** This broader term for "sexual immorality" or "fornication" often appears alongside μοιχεία. While *porneia* encompasses any illicit sexual activity, *moicheia* specifically denotes infidelity within a marriage. Adultery is a subset of *porneia*, but its specific violation of a covenant makes it distinct.
* **Old Testament Counterpart:** The Hebrew word נָאַף (na'aph, `{{H5003}}`) is the primary equivalent for "to commit adultery" in the Old Testament, prominently featured in the Decalogue ([[Exodus 20:14]], [[Deuteronomy 5:18]]). The Septuagint frequently translates na'aph with moicheuō, establishing a clear continuity of meaning and condemnation.
* **Covenant:** The concept of "covenant" is intimately linked to μοιχεία. Marriage is understood as a sacred covenant before God, and adultery is a profound breach of this covenant. The metaphorical use of adultery for idolatry further emphasizes this, portraying Israel's unfaithfulness to God as a violation of their divine covenant.
### Theological Significance
The theological significance of μοιχεία is profound and multifaceted:
* **Sanctity of Marriage:** The consistent condemnation of adultery throughout Scripture underscores the divine institution and sanctity of marriage. Marriage is presented as an exclusive, lifelong covenant between one man and one woman, reflecting the faithfulness of God to His people. Adultery defiles this sacred union ([[Hebrews 13:4]]) and violates God's design for human relationships.
* **Sin Against God:** While adultery is a sin against one's spouse and community, it is ultimately a sin against God Himself. As David confessed after his adultery with Bathsheba, "Against You, You only, have I sinned" ([[Psalm 51:4]]). It is a direct transgression of God's moral law and His holy character.
* **Source in the Heart:** Jesus' teaching in the Gospels reveals that the sin of adultery originates not merely in the physical act but in the lustful desires of the heart ([[Matthew 5:28]]). This highlights the internal nature of sin and the need for spiritual transformation and purity of thought, not just outward obedience.
* **Spiritual Adultery/Idolatry:** The metaphorical use of μοιχεία to describe spiritual unfaithfulness (e.g., [[Revelation 2:22]]) is a powerful theological concept. It portrays idolatry and devotion to false gods or worldly values as a betrayal of the unique and exclusive relationship God desires with His people. Just as a spouse demands exclusive devotion, God demands absolute loyalty from His covenant people. This metaphor emphasizes God's jealousy for His glory and His people's undivided worship.
* **Exclusion from God's Kingdom:** Adultery is consistently listed among the "works of the flesh" that prevent one from inheriting the Kingdom of God unless repented of ([[Galatians 5:19-21]]; cf. [[1 Corinthians 6:9-10]]). This underscores the serious spiritual consequences of such sin and the necessity of repentance and a transformed life in Christ.
### Summary
The Greek term μοιχεία (moicheía, `{{G3430}}`) precisely denotes the act of adultery, signifying sexual infidelity that violates the sacred marriage covenant. Throughout the New Testament, it is consistently condemned as a grave sin originating from the heart, demonstrating its profound impact on individuals, relationships, and one's standing before God. The term underscores the sanctity and exclusivity of marriage as a divine institution. Furthermore, μοιχεία serves as a potent metaphor for spiritual unfaithfulness and idolatry, powerfully illustrating God's demand for exclusive devotion from His people. Its inclusion in lists of behaviors that preclude entry into the Kingdom of God highlights its severe spiritual implications and the necessity of repentance for those who engage in it.
TRV