### Core Meaning & Semantic Range
The Greek verb μοιχάω (moicháō), Strong's number `{{G3429}}`, derives from the noun μοιχός (moichos), meaning "adulterer" (`{{G3432}}`). Its primary and unwavering meaning is "to commit adultery." This refers specifically to sexual intercourse between a married person and someone other than their spouse. The form often appears in the middle voice, emphasizing the active participation of the subject in the act of adultery. While its literal sense pertains to marital infidelity, the broader semantic range in biblical thought extends to spiritual unfaithfulness. In this metaphorical sense, it denotes idolatry or a breach of covenant loyalty to God, mirroring the Old Testament prophetic tradition where Israel's turning away from Yahweh was often depicted as spiritual adultery or harlotry.
### Biblical Occurrences & Contextual Analysis
The term μοιχάω (moicháō) and its cognates are central to the New Testament's ethical teachings, particularly concerning the sanctity of marriage.
One of the most profound uses is found in Jesus' Sermon on the Mount: "You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart" [[Matthew 5:27-28]]. Here, Jesus radicalizes the commandment, moving beyond the external act to the internal disposition of the heart, revealing the depth of God's moral standard. This interpretation highlights that sin originates not merely in action but in desire and intent.
The verb also appears in lists of the Ten Commandments when Jesus interacts with the rich young ruler, affirming its continued relevance under the New Covenant [[Matthew 19:18]], [[Mark 10:19]], [[Luke 18:20]].
In the narrative of the woman caught in adultery, though the specific verb μοιχάω is not used for her act, the context revolves around μοιχεία (moicheia - adultery, `{{G3430}}`) and the accusation that she was "caught in the act of adultery" [[John 8:3-5]].
Paul's epistles also reference μοιχάω or its related forms when addressing ethical conduct. In [[Romans 2:22]], Paul challenges the hypocrisy of those who preach against adultery but commit it themselves. Similarly, in [[James 2:11]], the apostle James emphasizes the unity of God's law, stating that to break one commandment, such as "You shall not commit adultery," is to become a transgressor of the whole law. The consistent use across various New Testament authors underscores the gravity of adultery as a sin.
### Related Words & Concepts
The word μοιχάω (moicháō) is part of a cluster of related terms that illuminate the biblical understanding of adultery:
* μοιχός (moichos - adulterer, `{{G3432}}`): The male participant in the act.
* μοιχεία (moicheia - adultery, the act itself, `{{G3430}}`): The noun form referring to the transgression.
* μοιχεύω (moicheuō - to commit adultery, `{{G3431}}`): Another common verb for the same act, often used interchangeably with μοιχάω.
* μοιχαλίς (moichalis - adulteress, `{{G3428}}`): The female participant; also used metaphorically to describe an unfaithful generation or people.
Beyond these direct cognates, μοιχάω is conceptually linked to:
* πορνεία (porneia - sexual immorality, `{{G4202}}`): Adultery is a specific, egregious form of porneia, which encompasses a broader range of illicit sexual acts.
* Covenant unfaithfulness: In the Old Testament, Israel's idolatry was frequently depicted as spiritual adultery against Yahweh (e.g., [[Ezekiel 16]], [[Hosea 1-3]]). This prophetic imagery carries into the New Testament, where spiritual unfaithfulness to God is likened to adultery (e.g., [[James 4:4]], which refers to "adulteresses" in a spiritual sense).
* Lust (ἐπιθυμία - epithymia, `{{G1939}}`): As highlighted by Jesus, the internal desire that precedes and can be equated with the act of adultery.
* Marriage: The divine institution that adultery violates, undermining its sacred bond and exclusive nature.
### Theological Significance
The theological significance of μοιχάω is profound, touching upon God's character, human relationships, and the nature of sin.
1. **Violation of God's Law and Holiness:** Adultery is a direct transgression of one of the Ten Commandments, reflecting God's righteous character and His demand for moral purity. It is an offense not only against one's spouse but ultimately against God Himself [[Psalm 51:4]].
2. **Sanctity of Marriage:** The prohibition against adultery underscores the sacredness and exclusivity of the marital covenant, established by God as a picture of Christ's relationship with the Church [[Ephesians 5:31-32]]. Adultery defiles this sacred union and breaks the covenant of fidelity.
3. **Jesus' Radical Standard:** Jesus' teaching in [[Matthew 5:27-28]] elevates the understanding of adultery from an external act to an internal state of the heart. This reveals the pervasive nature of sin and the need for inner transformation, not just outward conformity to the law. It challenges believers to pursue purity of thought and motive.
4. **Spiritual Adultery/Idolatry:** The metaphorical use of adultery to describe spiritual unfaithfulness to God is a powerful theological theme. Just as marital adultery breaks a sacred human covenant, idolatry or turning away from God breaks the divine covenant, demonstrating a lack of loyalty and devotion to the one true God. This imagery emphasizes God's jealousy for His people's exclusive worship and love.
5. **Exclusion from God's Kingdom:** The New Testament consistently lists adultery among the grave sins that exclude individuals from inheriting the Kingdom of God [[1 Corinthians 6:9-10]], [[Galatians 5:19-21]], underscoring its serious spiritual consequences unless repented of.
### Summary
The Greek verb μοιχάω (moicháō, `{{G3429}}`) fundamentally means "to commit adultery," referring to sexual infidelity within marriage. Its usage in the New Testament, particularly in Jesus' teachings, expands its scope from a mere external act to encompass the lustful desires of the heart, revealing the depth of God's moral requirements. The word is intrinsically linked to other terms describing the act, the participants, and the broader concept of sexual immorality. Theologically, μοιχάω highlights the sanctity of marriage as a divine institution, the pervasive nature of sin originating in the heart, and the profound breach of covenant loyalty—both human and divine. It serves as a stark reminder of God's holiness, His demand for purity, and the serious consequences of unfaithfulness, whether literal or spiritual.
TRV