In 1964, Supreme Court justice Potter Stewart defined obscenity, or hardcore pornography, by simply stating, “I know it when I see it.” Perhaps this was true for Stewart, or even the average American before the sexual revolution. Yet after decades of increasing promiscuity in media, fashion, and other cultural activities, we’re deeply desensitized to sexual immorality. We see it. But we don’t know it.
The normalization of pornography, “sex work” (e.g., OnlyFans), and LGBT+ ideology has dulled our moral sensibilities—and sins like polygamy, pedophilia, and incest are only a pair of binoculars away. This may seem to some like fear-mongering alarmism or a version of the slippery-slope fallacy so common in public dialogue today. But if you analyze United States laws, polling data, and media—along with a theological understanding of anthropology and sin—such a trajectory becomes arguable, even obvious.
Each of these sins can be argued directly from natural law, yet there are no squabbles between general and special revelation. Christians must be able to defend the sanctity of monogamous, male-female marriage and the beauty of chastity against the pagan practices of the modern age, so what follows is a biblical and theological response to polygamy, pedophilia, and incest.
Polygamy (Nonmonogamous Partnerships)
While polygamy is still technically illegal in the United States, it’s increasingly common for people to engage in open or polyamorous relationships, along with a host of other nonmonogamous relationship types. Polygamy is most common among Muslims in sub-Saharan Africa, though it’s still generally uncommon in most parts of the world. However, a 2020 Gallup poll discovered that one in five U.S. adults believes polygamy is morally acceptable (up 13 percent since 2003). Reality TV has normalized nonmonogamous relationships through shows with cult followings like The Bachelor (2002–24) and, recently, The Secret Lives of Mormon Wives (2024) and Couple to Throuple (2024).
Efforts to normalize nonmonogamy as a legitimate expression of sexuality have been especially strong in the LGBT+ community. But there’s also been a lesser-known push from right-wing manosphere figureheads like Andrew Tate, who claims polygamy is “perfectly normal” and that “the reason the Western world is so degenerate [is] because [men are] not allowed to live out their natural male instincts.” It’s even present in evangelical Christian circles: Vince Bantu, a church history professor at Fuller Theological Seminary, was recently accused of practicing and defending polygamy.
Biblical justification for polygamy has long been debated, given the examples of godly men with multiple wives in the Bible: Abraham, Jacob, David, Solomon, and so on. Furthermore, out of all the laws regarding marriage and sexuality in the Old Testament, none of them explicitly prohibits polygamy. Even in the New Testament, the only explicit call to monogamous marriages is for deacons and elders.
Yet these arguments are based on a simplistic reading of Scripture. They don’t take into account the varying ways that Scripture communicates. After all, there are many doctrines deduced from Scripture that are clear without being explicit (e.g., the Trinity). As the Westminster Confession of Faith attests, “The whole counsel of God concerning all things necessary for his own glory, man’s salvation, faith and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture” (1.6, emphasis added). Based on this principle, here are three basic arguments against all forms of nonmonogamous marriage.
1. God institutes marriage as a covenant between one man and one woman, while polygamy develops later, after the fall. As Jesus argued regarding divorce, “Because of your hardness of heart Moses allowed you to divorce your wives, but from the beginning it was not so” (Matt. 19:8). Likewise, God allowed polygamy and concubinage, but from the beginning it was not so. Rather, Scripture says, “A man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh” (Gen. 2:24).
2. Biblical authors frequently teach ethics through narrative. The text may not always explicitly say an individual’s action was morally right or wrong, but the consequences of their actions uphold certain virtues to be imitated and vices to be repented of. The first instance of polygamy is Lamech, a wicked man (4:19). Every time a patriarch takes multiple wives, it leads to jealousy, bitterness, and partiality (e.g., Gen. 29–30). It’s never promoted as a positive institution; it’s always shown negatively. And it’s explicitly prohibited for kings to take many wives (Deut. 17:17)—a command David and Solomon both disobey to their peril.
3. Deacons (1 Tim. 3:12) and overseers (v. 2; Titus 1:6) are required to be monogamous because they must conduct themselves as examples of godliness. They must be “the husband of one wife” in the same way they must be self-controlled, disciplined, hospitable, and not greedy for gain or quarrelsome. These prerequisites aren’t exceptions; they’re the standard description of a mature Christian. Shepherds and deacons act as imitators of Christ, who has one holy Bride, the church (Eph. 5:21–33), so that the sheep may follow in the same path of marital fidelity.
We can deduce “by good and necessary consequence” that we shouldn’t practice polygamy.
Incest
Incest may seem like a far cry from where we are today in the United States. However, it’s only slightly downstream from “Love is love.”
While it’s still fairly taboo in Western culture, consanguineous marriage is common in Northern Africa and the Middle East, for example: Pakistan (61.2 percent), Kuwait (54.3 percent), Qatar (54 percent), United Arab Emirates (50.5 percent), Sudan and South Sudan (50 percent), and Afghanistan (49 percent). Further east in India, the world’s most populous country, there are more than 50 million people (7.5 percent) in incestuous marriages. In the West, incest is pervasive in nonconsensual situations, given the majority of child molestations are by a close relative. But it’s increasingly necessary to emphasize that consent isn’t enough.
Incest has become more prevalent in entertainment (e.g., Game of Thrones). Although it’s likely more for shock value than for intentional normalization, it’s still there—and it’s at least symptomatic of a culture that enjoys heightening the threshold of perverted sexuality. It’s no coincidence that incest-themed porn, known as fauxcest, is one of the most searched categories on popular pornography sites. Research has shown a 178 percent increase in “family related porn,” along with the fact that one in ten purchases by young adults are for fauxcest titles.
We even have a new form of prostitution: “sugar daddies” and “sugar mamas.” These older benefactors provide financial resources in exchange for sexual favors. If you don’t spend a significant amount of time on social media, you may not realize how pervasive this is, but almost anyone from Gen Z immediately hears parental titles like “mommy” and “daddy” as somewhat sexualized—an indication we’re already living downstream from a fauxcest culture.
Incest is explicitly condemned in the Old Testament and the New Testament. In Leviticus 18:6, God prohibits incest: “None of you shall approach any one of his close relatives to uncover nakedness. I am the LORD.” The remainder of the passage (vv. 7–18) explains in detail the types of relations that are prohibited. In the New Testament, John the Baptist died defending the sanctity of marriage after Herod took his own sister-in-law as a second wife (Mark 6:17–28; cf. Lev. 18:16). In 1 Corinthians 5:1, Paul rebukes the church, saying, “It is actually reported that there is sexual immorality among you, and of a kind that is not tolerated even among pagans, for a man has his father’s wife” (cf. Lev. 18:8). There’s an obvious through line in Scripture regarding incest: it’s a sin.
There’s an obvious through line in Scripture regarding incest: it’s a sin.
Similar to polygamy, even when it’s not explicitly prohibited, it’s narratively taught to be wrong by good and necessary consequence. For example, Lot’s daughters intoxicate and have sex with him (Gen. 19:30–35), Judah sleeps with his daughter-in-law Tamar (38:18), Amnon forcibly rapes his half-sister Tamar (2 Sam. 13:7–14), and they’re all presented negatively. We’re expected to read the Levitical law into these stories.
Even in the case of Abraham with Sarah, who was his half-sister (Gen. 20:12), we should recognize they were already married when God called him at the age of 75 (12:4). The Lord told him, “Go from your country and your kindred and your father’s house” (v. 1), which was a household that “served other gods” (Josh. 24:2). Like his later descendants, Abraham was saved from a land that served foreign gods and brought into a covenant with the Lord—a covenant that required the circumcision of his foreskin, a sign of his sexual, procreative devotion to God alone.
Pedophilia
The sexualization of minors in various forms of media is ubiquitous, ranging from TikTok dances to films like Cuties (2020), Poor Things (2023), and the forthcoming Miller’s Girl (2024) to children’s books with sexual content. Hollywood’s recent fixation with May-December affairs (in this case, older women having sex with young men who could be their sons) illustrates the extent to which older adults lusting for younger bodies is being normalized.
In the realm of education, five U.S. states (California, Oregon, Washington, Colorado, and Illinois) have adopted Comprehensive Sexuality Education (CSE), normalizing youth sex and promoting progressive gender ideology. Consider the wide-scale promotion of “gender-affirming care” for children: social affirmation, puberty blockers, hormone therapy, “top” and “bottom” surgery. This is exacerbated by the recent push in states like California to create a “wall of secrecy” between children and their parents, which undermines the age of consent regarding sexual decisions.
This November, California residents will vote on Proposition 3, which seeks to remove language in the California constitution stating that marriage is between one man and one woman. But this isn’t merely an attempt to match the Supreme Court decision Obergefell v. Hodges (2015). According to the opposing argument in the General Election voter guide,
Proposition 3 removes all rules for marriage, opening the door to child marriages, incest, and polygamy. It changes California’s constitution even though same-sex marriage is already legal. By making moms and dads optional, it puts children at risk. This careless measure harms families and society.
This statement, backed by the California Family Council, expresses the crucial foresight we need to have. What would it mean for us to reject not only a biblical definition of marriage but any definition of marriage at all?
For a culture with the deeply embedded value that “consent is all that matters,” we don’t care nearly enough about protecting those who cannot give it. As one scholar argues, “To give legally valid consent, a person must possess the cognitive abilities to understand the basic nature of the marital obligation and to voluntarily agree to marry.” The same must be true of sexual decisions in general, including the ability to choose gender-affirming care.
Some may push back that in biblical times it was normal for an older man to marry a girl younger than 18, but the specific age of consent isn’t the point. An 18-year-old doesn’t have a radical cognitive change on her birthday, but we must enact laws that protect the dignity of all children based on evidence that proves an individual has the capacity to consent and perform marital acts.
For a culture with the deeply embedded value that ‘consent is all that matters,’ we do not care nearly enough about protecting those who cannot give it.
As with polygamy, some have attempted to destigmatize and decriminalize pedophilia in recent years, referring to pedophiles as “minor-attracted persons,” as if it were simply one of many sexual orientations. According to 41 police stations in the U.K., there was an 84 percent increase in online grooming crimes over four years (2018–22). The internet has increased and enabled grooming at an alarming rate: there are around 500,000 predators active online everyday, and an estimated 89 percent of sexual advances toward children happen through online chat rooms or instant messaging. Beyond mere advances, sexual abuse of minors is disgustingly high: at least one in five girls and one in twenty boys are sexually abused before they reach adulthood.
The obvious position of Christianity, since the inception of the early church, is that pedophilia is an evil and grievous sin. One of the earliest Christian documents, the Didache, condemns it under the category of “Gross Sin Forbidden”: “You shall not commit paidophthoros.” This is sometimes translated as an associated word, “pederasty” (paiderastes), which is an ancient term for grown men who have sexual relations with young boys. It was widely practiced and even honored in the Greco-Roman world, but it was unanimously rejected by Christian communities. There are numerous examples of church fathers condemning the practice, but they actually coined a new word for it: paidophthoros. Instead of using pederasty or its contemporary, pedophilia, which both mean something like child-lover, they spoke of paidophthoros: “one who sexually abuses/corrupts children.”
There’s something especially wicked about abusing a child. Herman Bavinck lists sex with children as a “sin against nature.” Song of Songs repeatedly warns against awakening love before its time (2:7; 3:5; 8:4); how much more should we rebuke those who awaken “love” before the natural maturation timeline of a child? The Mosaic law has clear laws against rape (e.g., Deut. 22:13–29), and we’re right to call sex with minors a form of it (i.e., “statutory rape”). Jesus said, “It would be better for him if a millstone were hung around his neck and he were cast into the sea than that he should cause one of these little ones to sin” (Luke 17:2). The vulnerable and helpless are most precious in God’s kingdom, and their abusers will not go unpunished.
Christian Response
Each of these practices is an evil perversion of God’s good design for sexuality. They’re not only against Scripture but against nature, given that marriage is a natural institution. But this acknowledgment is only an introduction to the problem, not a solution. How should we respond as Christians?
First, on the political level, we should create and reinforce laws that protect the innocent and vulnerable, restrict and punish sexual perversion, and promote the common good. We should vote and advocate against policies that compromise these goals. As public individuals with active roles in society, we should argue against the destigmatization of such practices and abstain from participating in forms of entertainment that promote them.
In local churches, we need to be prepared to minister to sexual sinners and answer pressing questions about the consequences of their actions. Should a man in a polygamous marriage opt for divorce? What if they have children? What about incestuous or pedophilic marriages? How do you love the victims well? How do you forgive a predator? This requires wisdom and courage.
While seeking full justice for crimes, we recognize that no one is beyond the saving and healing power of the Lord Jesus Christ. We must be willing to send someone to prison and then visit him with the good news that Christ sets prisoners free from sin’s bondage. Polygamists, pedophiles, and incesters can all be changed by God’s grace. “Such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God” (1 Cor. 6:11).
Most importantly, however, we must personally and corporately “flee from sexual immorality” (v. 18). We should display the glory of the gospel through the beauty of the Christian sexual ethic. The sanctity of marriage is—and will continue to be—the foundation of any flourishing society. We need strong marriages. The best thing a married man or woman can do to counter the sexual insanity of our world is to be a faithful, loving spouse. Teach this to your kids, show it to the neighbor’s kids, and infiltrate the internet and the arts with the beauty of holy matrimony.
The sanctity of marriage is—and will continue to be—the foundation of any flourishing society.
If you’re unmarried, you have the opportunity to extol the beauty of the Christian sexual ethic through chastity. The best thing a single man or woman can do is be a faithful, loving brother or sister: banish pornography and masturbation, avoid the allure of frivolous autonomy, and refuse to treat sex as anything less than sacred.
Whatever your situation, you can model sexual fidelity to a world that doesn’t know that sexuality is more than sex or that Jesus is more than sufficient.