Skip to main contentAccessibility feedback

Dear visitors: This website from Catholic Answers, with all its many resources, is the world's largest source of explanations for Catholic beliefs and practices. A fully independent, lay-run, 501(c)(3) ministry that receives no funding from the institutional Church, we rely entirely on the generosity of everyday people like you to keep this website going with trustworthy , fresh, and relevant content. If everyone visiting this month gave just $1, would be fully funded for an entire year. Do you find helpful? Please make a gift today. SPECIAL PROMOTION FOR NEW MONTHLY DONATIONS! Thank you and God bless.

Dear visitors: This website from Catholic Answers, with all its many resources, is the world's largest source of explanations for Catholic beliefs and practices. A fully independent, lay-run, 501(c)(3) ministry that receives no funding from the institutional Church, we rely entirely on the generosity of everyday people like you to keep this website going with trustworthy , fresh, and relevant content. If everyone visiting this month gave just $1, would be fully funded for an entire year. Do you find helpful? Please make a gift today. SPECIAL PROMOTION FOR NEW MONTHLY DONATIONS! Thank you and God bless.

The Real Sin of Onan

Among modern exegetes is has been fashionable to maintain that Genesis 38:9-10 condemns Onan’s coitus interruptus only insofar as it violated the so-called levirate marriage custom endorsed by the law of Moses at a time when polygamy was not forbidden. According to this ancient oriental practice, a man—whether he was already married or not—was expected to marry his deceased brother’s wife if she was childless at her husband’s death; the firstborn son of this union was regarded as a legal descendant of the dead man.

Those exegetes who focus their attention exclusively on this custom in their reading of Genesis 38 say Onan’s sin is presented here as consisting only in his selfish intent to deny offspring to his brother’s widow, Tamar, and not even partly in the unnatural method he employed in doing so.

But this reading has so little to recommend it exegetically that one can only assume its popularity is due to the modern prejudices of theologians and exegetes who see sterile types of sexual activity as morally unobjectionable in themselves (or even as necessary at times) and who therefore have a vested interest in minimizing whatever biblical evidence there may be against these practices.

Why was Onan worthy of death?

The classical Jewish commentators—who can scarcely be accused of ignorance regarding Hebrew language, customs, law, and biblical literary genres—certainly saw this passage of Scripture as a condemnation of unnatural intercourse. A typical traditional Jewish commentary puts it thus: “[Onan] misused the organs God gave him for propagating the race to unnaturally satisfy his own lust, and he was therefore deserving of death” (Bereshis: Genesis 5:1677). This is undoubtedly in accord with the natural impression that most unprejudiced readers will draw from the text of Genesis 38.

But is the truth really subtler? Was Onan perhaps slain merely for refusing to give offspring to his deceased brother’s wife, as most contemporary exegetes maintain? In answering these questions one must consider the following significant fact.

The penalty laid down in the law of Moses for a refusal to comply with the levirate marriage precept was only a mild public humiliation. The childless widow, in the presence of the town elders, was authorized to remove her uncooperative brother-in-law’s sandal and spit in his face for his refusal to marry her. He was then supposed to receive an uncomplimentary nickname—”the Unshod” (Deut. 25:8-10). But since he nonetheless became sole owner of his deceased brother’s house and goods, it is evident that his offense was scarcely considered a serious or criminal one, much less one deserving of death.

Death, however, is what Onan deserved, according to Genesis. It follows that those who say his only offense was breaking the levirate marriage custom need to explain why he was punished so much more drastically than was subsequently the case under the Mosaic law. If anything, we would tend to expect the contrary, that after the law was formalized as part of the Deuteronomic code its violation might be chastised more severely than before.

From explicit to allegorical

Indeed, a further problem faces this conventional modern reading of the passage. If simple refusal to give legal offspring to his deceased brother were Onan’s only offense, it seems unlikely that the text would have spelled out the crass physical details of his contraceptive act (verse 9).

The delicacy and modesty of ancient Hebrews in referring to morally upright sexual activity helps us to see this. Scripture always refers to licit (married) intercourse only in an oblique way: “going in to” one’s wife (entering her tent or bedchamber, verses 8 and 9 in the Genesis text cited above, as well as Genesis 6:4, 2 Samuel 16:22, 2 Chronicles 23:7) or “knowing” one’s spouse (see Genesis 4:17, Luke 1:34).

When the language becomes somewhat more explicit—”lying with” someone, or “uncovering [his/her] nakedness”—the reference is without exception to sinful, shameful sexual acts. Apart from the verse we are considering, the Bible’s only explicit mention of a genital act (the voluntary emission of seed) is in a prophetical context wherein Israel’s infidelity to Yahweh is being denounced scathingly in terms of the shameless lust of a harlot (see Ezekiel 23:20).

From this analysis the link between choice of words and moral evaluation in the Hebraic mentality is revealed. Broadly speaking, the sacred writers’ disapproval of different kinds of genital activity increases with the degree of explicitness with which they are described. Conversely, when sexuality is treated in its most sublime character—marriage as a sacred mystery symbolizing God’s covenantal love with his people—the Bible’s allusions to the conjugal act are predominantly indirect and allegorical. The implications of this for Genesis 38:9, where Onan’s sexual act is described in starkly explicit terms, are clear.

An emission of omission?

It should be remembered that the Israelite culture abhorred that other form of “wasting the seed”—the homosexual act—that it prescribed the death penalty for it (see Leviticus 18:22, 20:13). In the light of this and the other factors we have considered, it would be not only exegetically unwarranted but anachronistic to suggest that the Genesis author, in line with modern Western liberalism, would have taken a relaxed, indulgent view of Onan’s method of preventing conception—his “spill[ing] the seed on the ground.” We should note also the parallel between the description of homosexual acts as a “wicked” or “abominable” thing in the Leviticus texts and the similar qualification of what Onan did in Genesis 38:10.

In the view of revisionist exegetes, Onan’s sin is presented as being essentially one of omission. In other words, Onan committed no sinful act; rather, his sin was to refrain from acting appropriately toward his deceased brother because of a selfish disposition. But why, in that case, does the text describe Onan’s sin as a positive action (“he did a detestable thing”)? Coming directly after the author has mentioned what is certainly an outward act (“spilling the seed”), these words indicate a causal link between that sexual act as such and the wrath and punishment of God.

After all, it is not as if the Old Testament vocabulary was lacking in concepts or words to express sins of interior attitude. The “heart” of man—whether righteous or wicked—is a rich and important term of moral reference in Hebrew anthropology. To the extent that Onan’s fault was indeed this sin of omission, such lack of piety toward his dead brother would have been an example of what the Israelites called “hardness of heart” (see Exodus 7:13, 22; 8:15; Psalms 95:7f), perhaps motivated by vanity (not wanting to father any child who would not be legally his) or even by that sheer covetousness for his brother’s property that was forbidden in the Tenth Commandment and in numerous other Old Testament passages.

Once again we must ask what evidence there is that this “hardness of heart” would have been seen in Onan’s time as sufficient to merit death. If revisionist exegetes are right in claiming that “spilling the seed on the ground” is not, per se, censured in this text, it would follow that even if Onan had declined to marry Tamar and so abstained from intimacy of any kind with her, it would have been viewed by the Genesis author as no less offensive to God than the course of action which Onan chose in reality. But we have already pointed out that such a conclusion leaves unexplained the relative leniency of Deuteronomy 25 in penalizing such offenses against the levirate marriage custom.

A violation on natural law

On the other hand if, as Judeo-Christian tradition always has insisted, “wasting the seed” by sterile types of genital action violates that natural law to which all men, Jew and Gentile alike, have access by virtue of their humanness (see Romans 1:26–27, 2:14), this explains why Onan’s sexual action in itself would be presented in Scripture as meriting a most severe divine judgment. It was a perverted act, one of life-suppressing lust.

Indeed, over and above its prohibition by natural law, such deliberately sterilized pleasure-seeking could well have been discerned as contravening one of the few divine precepts that already in that pre-Sinai tradition had been solemnly revealed—and repeated—in positive, verbal form: “Increase and multiply” (Gen. 1:27-28, 9:1).

The cumulative weight of the evidence—the structure and sexual explicitness of the text itself and the much greater severity of Onan’s punishment than that prescribed for levirate marriage infringements in Deuteronomy 25:5-6—leads us to conclude that while Genesis 38:9-10 probably includes disapproval of Onan’s lack of piety toward his deceased brother, it is nonetheless the unnatural sex act in itself that is presented as the most gravely sinful aspect of this man’s treatment of Tamar—the aspect for which God cut short his life.

If the inspired author, while knowing the same historical facts, had evaluated them in the way most modern exegetes would have us believe he did (with moral indifference toward Onan’s contraceptive act as such), we would expect quite different wording. “Spilling the seed,” being irrelevant to the author’s interest and purpose on that hypothesis, would not even have been mentioned. Instead, we would expect to be faced with an account stating more discreetly that, even though Onan took Tamar legally as his wife, he refused to allow her to conceive, so that God slew him for his “hardness of heart,” his pride, or perhaps his avarice (in wanting his brother’s property to pass to himself and his own sons).

Thus, the traditional interpretation of this passage as a divinely revealed condemnation of contraceptive acts—not as a provision of mere positive law (cultic or disciplinary) given temporarily for a specific ancient cultural context, but as a particular manifestation of that divine will which had been revealed through nature ever since the Creation—must be seen as supported by serious exegetical arguments. Quite apart from those arguments, and even without any appeal to the Catholic theological principle that Church Tradition must be our guide to the interpretation of Scripture, a purely historical awareness of the unanimity of Jewish tradition on this point highlights how implausible and anachronistic is the view we are criticizing.

That view involves the gratuitous suggestion that the ancient author of Genesis 38 was a lone “liberal” who, in contrast to every other Jewish commentator until recent times, was unaccountably permissive about unnatural sex acts while at the same time, paradoxically, showing himself (and God) to be unaccountably severe in regard to infractions of the levirate marriage custom.

The witness of Christian as well as Jewish tradition on this point should be emphasized. That Onan’s unnatural act as such is condemned as sinful in Genesis 38:9-10 was an interpretation held by the Fathers and Doctors of the Catholic Church, by the Protestant Reformers, and by nearly all celibate and married theologians of all Christian denominations until the early years of the twentieth century, when some exegetes began to approach the text with preconceptions deriving from the sexual decadence of Western culture and its exaggerated concern for “over-population.”

Sad to say, these preconceptions have since become entrenched as a new exegetical “orthodoxy” that no longer can see in this scriptural passage even a trace of indignation against intrinsically sterile forms of genital activity.

Did you like this content? Please help keep us ad-free
Enjoying this content?  Please support our mission!