Marriage to a Brother’s Wife is Forbidden by Divine Command

Church Laws
Marriage to a Brother’s Wife is Forbidden by Divine Command
This prohibition is mentioned twice consecutively in the Book of Leviticus, where God commands:
A. “If a man takes his brother’s wife, it is impurity. He has uncovered his brother’s nakedness. They shall be childless.” (Leviticus 20:21).
B. Among the forbidden kinship marriages: “You shall not uncover the nakedness of your brother’s wife; it is your brother’s nakedness.” (Leviticus 18:16).
These are sacred texts from the Law, spoken by the Lord to Moses for the people. Therefore, we are bound by this divine and holy command. How could one allow a marriage that God Himself described as impurity?
The only exception—no longer applicable today—appears in Deuteronomy (25:5–9), under three conditions:
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A man dies having no son.
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His brother takes the widow to raise offspring for the deceased brother, so that the firstborn son would bear the name of the dead brother, not the living one.
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The reason: “That his name may not be blotted out from Israel.”
If the deceased brother already had offspring, it was then forbidden for his brother to marry the widow, according to (Leviticus 20:21) and (Leviticus 18:16).
Thus, marriage to a brother’s wife in order to “care for his brother’s children” contradicts the Holy Scripture. The Bible only permitted such a union to raise offspring for a deceased brother who had none. Therefore, it was commanded: “The wife of the dead shall not be married outside to a stranger.” (Deuteronomy 25:5).
Saint John Chrysostom explained (on Matthew 14) that a stranger was not obliged to raise offspring for the deceased husband, but the brother was—to bear children in his brother’s name.
Today, no one can attribute a child to a deceased brother, nor do legal systems allow it, nor is there any benefit. The phrase “that his name may not be blotted out from Israel” (Deuteronomy 25:6) no longer applies.
It is forbidden to marry one’s wife’s sister or one’s husband’s brother.
If a woman marries her husband’s brother, it means that man has married his brother’s wife—explicitly forbidden by God in Leviticus. It is unreasonable that a marriage forbidden in the Old Testament should be allowed in the New Testament, which calls for greater perfection.
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Our good God, who forbade a man to marry his brother’s wife, gave no importance to the supposed “goodness” of the brother in caring for his deceased brother’s children. The divine revelation clearly declared such a marriage to be impurity (Leviticus 20:21).
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John the Baptist reproved Herod for marrying his brother’s wife. Some think the rebuke was because Herod took her while his brother was still alive—but John specifically said, “It is not lawful for you to have your brother’s wife,” recalling the divine prohibition (Leviticus 18:16).
This divine command existed about twenty centuries before Emperor Justinian’s time, so claiming it was a civil law, not an ecclesiastical one, is unreasonable. The prohibition was divine, from the time of Moses in the fifteenth century B.C.
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Nevertheless, the Church also forbade this marriage in canon law. The second canon of the Council of Neocaesarea (314–315 A.D.) states:
“If a woman marries two brothers, she shall be cast out from communion until her death.”
This means she is excommunicated, unless she repents and dissolves the marriage. The canon adds that if one spouse dies before dissolution, repentance for the surviving party becomes difficult, since they remained in a sinful union without repentance.
Marriage to a wife’s sister is also forbidden by Church canons.
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Saint Basil the Great forbade it in his canons—he whose liturgy we still celebrate and whose absolution we pray. In Canon 23, he says:
“A man shall not marry his wife’s sister, nor shall a woman marry her husband’s brother.”
This is a clear ecclesiastical law, included in his second canonical letter to Amphilochius, Bishop of Iconium.
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Saint Basil reinforced this in Canons 76 and 78, imposing penalties on those who marry a brother’s wife or daughter-in-law, or marry two sisters in succession. Canon 23 further says:
“He who marries his brother’s wife shall not be admitted to communion until he dismisses her.” -
In Canons 87 and 88, in a letter to Diodorus of Tarsus (and copied to Amphilochius), Saint Basil wrote:
“He who marries his wife’s sister, his marriage is not lawful, and neither man nor woman may enter the church until the marriage is dissolved.”
All these are ecclesiastical, not civil laws, issued long before emperors like Theodosius or Justinian.
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Saint Timothy of Alexandria (22nd Patriarch) also forbade it in Canon 11. When asked whether clergy could bless a marriage known to be unlawful because of kinship (such as a widow marrying her husband’s brother), he replied:
“No, a clergyman must not cooperate with those who transgress the Law.” -
Because this marriage is forbidden, the Apostolic Canons exclude from ordination anyone who has ever committed it. Canon 19 states:
“Whoever marries two sisters, or a woman and her niece, or his niece, shall not be admitted to the clergy,” even if he repents and dissolves the marriage. -
The Sacred Synod under Pope Cyril Ibn Laqlaq (13th century) also prohibited such marriages. This Synod, one of the most important in the Middle Ages, included great saints like Anba Boulos El-Boushy and declared:
“No one shall marry his wife’s daughter or her descendants, nor her sister or her descendants, nor her aunt, nor her uncle’s wife, nor her mother, nor her father’s wife, nor her grandmother, nor her grandfather’s wife.”
It also says:
“No one shall marry his brother’s wife or her descendants, nor her mother nor her grandmother.” -
Thus, not only the wife’s sister is forbidden, but all her close female relatives, as are those of a brother’s wife.
One final note:
Everything mentioned above concerns divine law and ecclesiastical canons forbidding marriage to a brother’s wife or a wife’s sister. Civil laws made by emperors are irrelevant. If civil law agrees with Church law, it merely follows divine truth; if it contradicts it, it is not Christian.
Therefore, our discussion concerns only Church canons. Within these alone, we affirm the prohibition of marriage to a brother’s wife, a wife’s sister, a father’s wife’s sister, and all other degrees of kinship that constitute marriage impediments.
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