Marriage based on mutual love and intimacy is seen as a standard solution to avoid sex related sins. However, the institution of marriage has its own limits and to cross the defined boundaries is a sin.
Some fringe Hindu cults that practiced Tantric orgiastic rites may have had rituals leading to incestuous relationships, but other than that, all major world religions, including Hinduism, strictly forbid incest, considering it a grave sin, and marriage between close relatives, therefore, is clearly forbidden. Family members with blood-ties or relations through marriage, such as brother and sister, parent and offspring, uncle and niece, aunt and nephew, granddaughter and grandfather, daughter-in-law and father-in-law, stepmother and stepson, and others belonging to a well-knit family system are under rigid prohibition of marrying each other, such as in the Bible (Leviticus 18:6-18) and the Qur’an (4:23), both of which provide detailed lists of these prohibitions.
In Islam, a foster mother who nurses a child is regarded as if she is the natural mother of the child. Such a foster child, on becoming an adult, cannot marry any one of the foster mother’s children or her other relatives by blood or marriage. However, marriage between first cousins is allowed in most of the organized religions; but with the passage of time, although not considered sinful, it has been made primarily illegal for genetic reasons. In Mosaic Law as well as Islamic Shariah, where polygamy is permitted, a man cannot marry his wife’s sister during his wife’s lifetime; neither can he marry a woman and her daughter from her previous marriage, nor can he marry a woman and her mother at the same time. Among the Jews, a marriage to such close kin was considered so horrendously appalling that in the Torah it is called a curse, and its prescribed punishment was stoning the sinners to death and burning their bodies (Leviticus 20:14).
Sex and Impurity
According to scriptural commentators in Judaism and Islam, sexual activity, or secretion of the seminal fluid, makes the human body unclean; therefore, taking a ritual bath is required after ejaculation or sexual intercourse. Moreover, the Bible and the Qur’an state that a woman is ritually unclean during her monthly period. Sexual intercourse with a woman during her menstrual period would make her husband ritually impure as well (Leviticus 18:19). Therefore, it is considered a sin for a husband to cohabit with his wife during her menstrual period. In Biblical times, this sin too was worthy of severe punishment. Menstruation was considered a kind of ‘sickness’, and the Bible declares: “If a man lies with a woman during her sickness and uncovers her nakedness, he has exposed her flow, and she has uncovered the flow of her blood, both of them shall be cut off from their people (Leviticus 20:18). The wife is required to take a ritual bath before resuming marital relations, entering a place of worship, or holding the Holy Scriptures, in case she contaminates the things she touches.
(To be continued…) (Source: Enigma of Sin by Mubasher Ahmad)