Leviticus 18:19–23

Leviticus 18:19 — Approaching a Woman in Her Impurity The prohibition against sexual intercourse during a woman's menstrual period (niddah in Hebrew) is rooted in the Levitical purity system in which blood is a uniquely sacred substance — the bearer of life itself (Lev 17:11). This is not a statement about the woman's moral unworthiness, but about the sacred weight of blood and the need for Israel to treat life's biological rhythms with reverence. The phrase "uncover nakedness" (galah erwah) is the chapter's repeated idiom for sexual union, carrying overtones of exposure and vulnerability that demand protective respect rather than exploitation. In the broader structure of chapter 18, this verse serves as a transition between the incest laws (vv.6–18) and more public or cultic violations, situating bodily holiness within both domestic and communal spheres. Ezekiel will later cite violation of this law among the sins that brought judgment on Israel (Ezek 18:6; 22:10).

Leviticus 18:20 — Adultery with a Neighbor's Wife Adultery is here framed not merely as a property violation against the husband (as some ancient Near Eastern codes treat it) but as a defilement of oneself — the adulterer damages his own moral and spiritual integrity. The word "carnally" (shekhoveth zera, literally "a lying of seed") specifies sexual union in the most direct biological terms, anchoring the prohibition in the physical act. The neighbor's wife is explicitly named, echoing the Decalogue's prohibition (Ex 20:14; Deut 5:18) and anticipating the Sermon on the Mount, where Jesus will interiorize this command to the level of desire (Matt 5:27–28). Catholic moral theology, drawing on this verse, understands adultery as a violation of the covenantal bond that mirrors God's faithful covenant with Israel.

Leviticus 18:21 — Child Sacrifice to Molech and the Profaning of God's Name This verse is striking in its placement within a list of sexual prohibitions, and its position is theologically significant rather than editorially careless. Ancient scholarship (and modern archaeological evidence from Carthage and the Levant) confirms that the cult of Molech involved the immolation of children — possibly the firstborn — as a ritual offering. The Rabbis and many Church Fathers understood the juxtaposition with sexual sins as deliberate: disordered sexuality and idolatry are spiritually linked. Children conceived through illicit unions might be sacrificed to cover the sin, or the offering of children is itself a sexual idolatry — the gift of life perverted into a religious spectacle. The phrase "profane the name of your God" (chilalta et-shem Elohekha) introduces the concept of Kiddush Hashem (sanctification of the Name) by its negative: every moral violation of this code is a desecration of the divine Name, not merely a private wrong. The solemn declaration "I am Yahweh" grounds the entire section in divine self-revelation — these are not sociological norms but reflections of who God is.

Leviticus 18:22 — Male Homosexual Acts The text uses the same vocabulary of "lying with" as the preceding adultery prohibition, establishing a grammatical and moral parallel. The act is described as toevah — "detestable" or "abomination" — a word used in Leviticus and Deuteronomy specifically for practices associated with Canaanite religion and idolatry (cf. Deut 18:9–12), as well as for things fundamentally contrary to right order. This is not merely ritual uncleanness (as with v.19) but a category of moral disorder. Catholic exegesis has consistently held, from the Church Fathers through the Catechism of the Catholic Church, that this prohibition reflects the natural moral law as perceived through creation's design — male and female made for one another in fruitful complementarity (Gen 1:27–28).

Leviticus 18:23 — Bestiality Both male and female forms of this act are explicitly condemned — unusual in a legal code that often defaults to male-subject grammar — suggesting the legislator wished to close every possible interpretation. The word "perversion" (tevel) appears only here and in Lev 20:12 (incest), indicating a category of ultimate confusion of kinds, a violation of the orders God set within creation. For Israel, bestiality may also have had cultic associations: Egyptian and Canaanite fertility cults included animal-human imagery with possible ritual enactments. The mixing of human and animal sexuality strikes at the heart of the imago Dei — the unique dignity of the human person who stands above the animal order as image-bearer of God.

Typological and Spiritual Senses At the typological level, the holiness code of chapter 18 points forward to the Church as the new Israel called to a radical distinctiveness from the "nations" (vv.24–30). The body of the baptized Christian is a temple of the Holy Spirit (1 Cor 6:19), making every sexual sin a sacrilege against a sacred dwelling. The prohibition against Molech-worship finds its antitype in every culture that sacrifices children — whether by ancient fire or modern convenience — on the altar of self-will.

Catholic tradition reads these verses not as culturally-conditioned Israelite taboos but as divine law rooted in the natural moral order that reason itself can discern, and which divine revelation confirms and clarifies. The Second Vatican Council's Gaudium et Spes (§51) affirms that "the moral goodness of acts" in the sexual sphere "does not depend solely on sincere intentions or on an evaluation of motives. It must be determined by objective standards." Leviticus 18 is one of the scriptural pillars of that objective standard.

On verse 21, the Catechism (§2113) explicitly treats idolatry as encompassing the sacrifice of human life, connecting the Molech prohibition to any ideology that subordinates human dignity to an absolute — a teaching that resonates through Catholic social teaching's opposition to abortion and euthanasia.

On verse 22, the Catechism (§2357) cites both Leviticus 18:22 and Romans 1:24–27 in its teaching that homosexual acts are "intrinsically disordered," meaning contrary to the natural law regardless of intent or consent, because they cannot fulfill the unitive and procreative ends of sexuality as God designed it. St. John Chrysostom (Homily IV on Romans) and St. Augustine (Confessions III.8) both treat such acts as violations of the order inscribed by the Creator in nature itself. Importantly, the Catechism (§2358) immediately distinguishes the acts from persons, calling for compassion and respect.

St. Thomas Aquinas classified the sins listed here under "sins against nature" (Summa Theologiae II-II, q.154, aa.11–12), meaning they contradict the teleological order God has inscribed in human sexuality — an order oriented toward procreation within permanent, faithful, complementary union. This teleological reading unifies verses 19–23 as a set: each prohibition protects the sacred order of sexuality as gift, covenant, and life-giving communion.

These verses challenge contemporary Catholics on several concrete fronts. First, verse 21's Molech prohibition invites an examination of conscience about modern idolatries that demand the sacrifice of human life or dignity — a summons directly relevant to Catholic engagement with bioethical debates. Second, the passage as a whole challenges the cultural pressure to treat sexual ethics as merely a matter of personal preference, reminding Catholics that the body is a theological reality, not a neutral instrument of self-expression. For Catholics living in an era that celebrates sexual autonomy as the supreme moral category, Leviticus 18 offers not a weapon for judgment of others but a mirror for personal integrity. The repeated phrase "I am Yahweh" is the key: every sexual act is implicitly an act of theology — it either honors or profanes the God in whose image the body was made. Concretely, this passage calls Catholics to pursue regular examination of conscience regarding chastity according to their state in life, to engage bioethical questions with informed conviction, and to hold together — as the Catechism does — moral clarity about acts with genuine mercy toward persons.