But a careful reading of the Holy Scriptures reveals a much more nuanced, complex approach to physical intimacy.
Adultery, incest, prostitution, virginity, rape, ways to please a spouse, advice about frequency of sex, homosexuality, polygamy, masturbation, menstruation and nocturnal emissions--they're all there.
Some figures, like King David, break the rules and still are portrayed positively. And one whole book, Song of Solomon, celebrates erotic love between a man and a woman.
"When I studied the Bible, I was surprised to discover a much more positive view of sexuality than I had ever known," says Debra Haffner, a former sexologist who is now studying to be a Unitarian Universalist minister in New York City. "It wasn't what I was taught in Sunday school growing up."
The book, revered as scripture by Jews, Christians, and Muslims, celebrates sexual love as a source of intimacy and pleasure that needs to be exercised carefully, lest it be a source of pain and distress, says Haffner, past president of SIECUS (Sexuality Information and Education Council of the United States).
Indeed, more and more people are turning to the Bible and their own religious traditions for help with sexual relationships.
Last year, Rabbi Shmuley Boteach wrote "Kosher Sex: A Recipe for Passion and Intimacy," which draws its lessons from the Bible.
"Unlike other religious traditions, Judaism has never had a prudish or conservative sexual ethic," Boteach writes in the book's introduction.
For example, Boteach says that the ancient rabbis "made female orgasm an obligation incumbent on every Jewish husband. No man was allowed to use a woman merely for his own gratification."
In a similar vein, a recent book about sex aimed at Mormons has been flying off the shelves.
"Between Husband & Wife--Gospel Perspectives on Marital Intimacy," by Stephen E. Lamb and Douglas E. Brinley, has sold more than 70,000 copies, even outselling "Standing for Something," the recent book by LDS Church President Gordon B. Hinckley, in LDS-owned Deseret Book stores.
Though the book is liberally sprinkled with churchy advice from LDS presidents and apostles, Lamb, a Salt Lake City obstetrician, and Brinley, a Brigham Young University church history professor, also offer candid advice about such issues as the importance of foreplay and female orgasm, as well as problems such as painful sex, endometriosis and premature ejaculation, sex during pregnancy and postpartum, impotence, and differing expectations regarding how often to have intercourse.
One obvious omission is any straightforward discussion of oral sex, which is only alluded to in a section on using restraint and "unnatural behavior."
But the overall message is clear--even revolutionary--for some members of The Church of Jesus Christ of Latter-day Saints: God intends married couples to enjoy sexual intimacy.
That idea began in the Bible. In the Garden of Eden, Adam and Eve were blissfully naked and chaste but commanded by God "to multiply and replenish the Earth."
After they were expelled from the Garden for disobeying God by "eating from the Tree of Knowledge of Good and Evil," the Bible says that "Adam knew Eve his wife and she conceived, and bare Cain."
There are several biblical terms for sex, according to "A Dictionary of Sex in the Bible," an online publication by Ronald L. Ecker.
Old Testament writers use the verb bo ("to enter" or "to go into" ) or the euphemisms "to lie with" (yashav) and "to know" (yada). "To know" in this sense is subsequently found also in Greek, as ginosko, Ecker writes.
It is not clear how many times Adam and Eve had sex after that, but the account in Genesis says "Adam begat sons and daughters" for 800 more years.
Clearly, procreation was a concern for the early Hebrews, says the Rev. Charles Henderson, a Presbyterian minister in New York who has written extensively about sexuality and religion.
"The Bible was written at a time when the people of Israel and Judea were not very numerous. They were surrounded by larger, more powerful countries, so naturally they had a profound concern for the size of the population," Henderson says. "Much of what one might call a biblical perspective on sexuality has to do with an overarching concern for procreation."
"Male semen was thought to be all that was necessary to produce life," Henderson says. "The woman was merely a holding place for the male 'seed.'"
Women also were viewed as property. Thus, while a woman was required to be faithful to her husband, in the Old Testament a married man could have sex outside of marriage and not be an adulterer.
Under the Hebrew patriarchal system, a man committed adultery only if he had sex with another man's wife or a betrothed virgin--in effect a property crime, Ecker writes.
The Bible lays out many other rules for appropriate sexual relations between spouses.
No sex during menstruation. Abstinence during times of worship ("Come not at your wives"--Exodus 19:15) and warfare (1 Samuel 21:4-5; 2 Samuel 11:11). A newly married man, however, was given a year off from war and other work to stay home and "cheer up his wife" (Deuteronomy 24:5), Ecker writes.
But there are many exceptions.
Lot's daughters, fearing they will never have children after fleeing their home in Sodom and Gomorrah, get their father drunk and have sex with him.
The story of Samson and Delilah is about "sexual bondage," says Haffner. It tells of Samson, whose superhuman strength came from never cutting his hair. One of his consorts, Delilah, asks him about his prowess, and he replies that if he is bound with "seven green bowstrings that have not been dried, he will be as weak as any man." But she tries it, and he easily snaps the bowstrings.
Ecker describes the incident as "a kinky sex game."
"Who knew that was in there?" Haffner wonders.
And if you think the question of female sexual pleasure is a modern issue, think again, Haffner says.
"There is a remarkable amount of it in the book of Genesis," she says.
For example, when Sarah, wife of Abraham, is in her 90s, she asks, "Am I to receive pleasure again from my husband?"
But no biblical story shows the complexity of sexual relationships more completely than King David, recounted in the book of Second Samuel.
There is adultery (with Bathsheba), murder (of Bathsheba's husband), and incest (David's son Amnon rapes his virginal half-sister Tamar). When King David was in his dotage, his aides found a "virgin to live by him and keep him warm," though he did not "know her."
But no matter what sexual rules David broke, he continued to be a beloved figure among Jews. Even Jesus Christ's lineage as outlined in the New Testament is traced purposely to David.
Speaking of Jesus, he had little to say about sexual relations.
"That is not surprising, since Jesus was not married and caught up in other issues," Henderson says. "Jesus never said settling down with a wife and children was wrong, and he had many female friends."
Jesus was driven by a sense of urgency for his mission, he says, "like a road warrior in today's cyberworld."
By contrast, Paul, also unmarried, had a lot to say about sex. He was the first to elevate celibacy above procreation, Henderson says.
Believing the world would soon end makes Paul and the early Christians' position more understandable.
"Getting married and having children was not their first priority," Henderson says.
Later Christians, beginning with Augustine in the first century, believed that "sexual desire is sinful; that infants are infected from the moment of conception with the disease of original sin; and that Adam's sin corrupted the whole of nature itself," says scholar Elaine Pagels in her book "Adam, Eve & the Serpent." That explains, in part, the tradition of Catholic guilt and celibate priests.
Celibacy is a foreign concept in Judaism, Boteach says. And so is guilt about past sexual encounters.
"The essence of Jewish thought is . . . always move forward," he says. "Never become mired in your past. We can always reclaim our innocence."
Today, many religious traditions promote sexual satisfaction in marriage.
The prophet Muhammad condemned premarital sex and adultery, anal intercourse and forced sex, but celebrated sexual union among spouses.
It "prefigures the felicity of paradise, and eroticism within marriage is condoned," says the Encyclopedia of Islam.
The Qur'an says, "Your women are your fields; go to your fields as you wish."