The Bible outlines various relationships considered forbidden, primarily categorizing them by degrees of kinship (incest), moral conduct, and spiritual purity. These prohibitions aim to uphold societal order, maintain family integrity, and reflect divine standards of holiness.
Prohibited Degrees of Kinship (Incest)
A significant portion of forbidden relationships in the Bible, particularly in the Old Testament, concerns sexual relations and marriage between close relatives. These prohibitions, detailed mainly in Leviticus chapters 18 and 20, define what is considered incestuous. The purpose of these laws often relates to preventing moral degradation, promoting public health, and distinguishing the Israelites from surrounding nations.
The forbidden relationships by kinship include both consanguinity (blood relatives) and affinity (relatives by marriage). Specific examples mentioned in biblical texts, which include those generally understood to be forbidden, are presented below:
| Relationship Category | Specific Forbidden Connection | Relationship Description |
|---|---|---|
| By Blood | Mother | Sexual relations with one's own mother are strictly forbidden. |
| (Consanguinity) | Daughter | Sexual relations with one's own daughter are strictly forbidden. |
| Sister / Half-sister | This includes sisters born of the same father or the same mother, or both. | |
| Granddaughter | The daughter of one's son or daughter. | |
| Aunt | A parent's sister (either paternal or maternal aunt). | |
| Niece | The daughter of one's brother or sister. While not always explicitly listed with penalties in the same way as other relationships, it falls within the spirit of prohibited close kinship for marriage and sexual relations in many interpretations of biblical law. | |
| By Marriage | Father's wife (Stepmother) | Sexual relations with one's father's wife, even if she is not one's biological mother. This prohibition extends even after the father's death. |
| (Affinity) | Mother-in-law | Sexual relations with the mother of one's spouse. |
| Daughter-in-law | Sexual relations with one's son's wife. | |
| Uncle's wife | The wife of one's father's brother. | |
| Brother's wife | Generally forbidden, with the notable exception of the levirate marriage law (Deuteronomy 25:5-10), which mandated a brother to marry his deceased brother's childless widow to continue the family line. | |
| Wife's daughter (Stepdaughter) | Sexual relations with a stepdaughter are forbidden. | |
| Wife's granddaughter | Sexual relations with the daughter of one's wife's son or daughter. | |
| Two sisters simultaneously | A man is forbidden from marrying or having sexual relations with two sisters at the same time, particularly during the lifetime of the first sister. |
These laws underscore the Bible's emphasis on distinguishing family units and maintaining clear boundaries within kinship structures.
Other Forbidden Relationships and Practices
Beyond kinship, the Bible prohibits various other types of relationships and sexual practices based on moral, ethical, and spiritual grounds:
Adultery and Fornication
- Adultery: Engaging in sexual relations with someone other than one's spouse. This is explicitly forbidden in the Ten Commandments (Exodus 20:14, Deuteronomy 5:18) and throughout both the Old and New Testaments, often carrying severe penalties.
- Fornication: A broader term generally referring to any sexual activity outside the bounds of marriage. This includes premarital sex and other illicit sexual acts. The New Testament strongly condemns fornication, emphasizing purity and self-control (e.g., 1 Corinthians 6:18, Galatians 5:19).
Homosexual Relationships
The Bible, particularly in the Old Testament (e.g., Leviticus 18:22, Leviticus 20:13) and reiterated in the New Testament (e.g., Romans 1:26-27, 1 Corinthians 6:9-10), prohibits sexual relations between individuals of the same sex. These acts are described as an abomination or contrary to God's created order.
Bestiality
Sexual intercourse with animals is explicitly forbidden and considered an abomination, punishable by death (Leviticus 18:23, Exodus 22:19). This prohibition highlights the distinction between humans and animals and underscores the sanctity of human sexuality.
Prostitution
Both male and female cultic prostitution (associated with idolatrous worship) and general prostitution are condemned (Deuteronomy 23:17-18, Leviticus 19:29). Prostitution is seen as defiling and a departure from spiritual and moral purity.
Marriage to Non-Believers/Specific Nations (Historical Context)
For ancient Israel, certain marriages were forbidden, particularly with people from specific pagan nations (e.g., Deuteronomy 7:3-4). This prohibition was primarily to prevent spiritual apostasy and maintain the purity of Israel's worship of the one God, rather than a general rule for all peoples across all times. The New Testament generally advises believers to marry "only in the Lord" (1 Corinthians 7:39), emphasizing shared faith rather than ethnicity.
These various prohibitions reflect the biblical emphasis on holiness, the sanctity of marriage, and the moral conduct expected of individuals and communities seeking to live in accordance with divine will.
