What the Bible Says About Contraception

When we Catholics defend our Church’s teaching about contraception, we almost always use philosophical arguments that appeal to the natural law without relying on God or revelation. These kinds of arguments are great, as they can appeal to people of any faith (or even no faith), but there is another approach we can take as well, one that is particularly helpful when discussing the issue with other Christians: we can look to the teaching of Scripture on the subject. The Bible does not explicitly address the morality of contraception, but there is a passage that very strongly implies that it’s wrong.

The Story of Onan

In the book of Genesis, we find the story of a man named Onan, the most famous and (to my knowledge) only user of a contraceptive method in all of Scripture. Granted, modern contraceptive methods were not around in biblical times, but the ancients did have ways of making their sex non-procreative, and Scripture tells us that Onan used one such method:

“Then Judah said to Onan, ‘Go in to your brother’s wife, and perform the duty of a brother-in-law to her, and raise up offspring for your brother.’ But Onan knew that the offspring would not be his; so when he went in to his brother’s wife he spilled the semen on the ground, lest he should give offspring to his brother. And what he did was displeasing in the sight of the Lord, and he slew him also.” (Genesis 38:8-10)

This passage can be a bit confusing for us 21st century Americans, so let me give a bit of background. In ancient Israel, when a married man died childless, it was his brother’s duty to marry his widowed sister-in-law and have a child with her, and that child would legally be considered the dead man’s heir.

Once we understand the cultural context, the story becomes easy to follow. Onan’s brother died without any kids, so it was Onan’s responsibility to have a child with his sister-in-law. However, he knew the child would not be his, so when they had sex, he used an ancient method of birth control (pulling out before ejaculating) to render their sex non-procreative. This angered God, so he punished Onan by killing him.

The Big Question

The story raises an obvious question for us: what exactly was wrong with Onan’s action? Unfortunately, the text doesn’t give us an answer, so we have to figure it out for ourselves. Essentially, there are three possible reasons for God’s anger with Onan:

  • 1) Onan’s sin was refusing to perform “the duty of a brother-in-law.”
  • 2) Onan’s sin was failing to continue the line of the patriarch Judah (his father), the line from which Jesus would eventually come.
  • 3) Onan’s sin was using an ancient method of contraception.

So which is it? Which of these three is the reason God killed Onan? To figure that out, we need to read the story in the larger context of Scripture as a whole, and when we do that, we’ll find that the answer becomes pretty clear.

The Wrong Answers

Let’s begin by considering the first possible answer.  Did God kill Onan simply because he failed in his duty to his sister-in-law? Probably not. If we look at the rest of the Old Testament, the punishment in ancient Israel for this kind of sin was not death (Deuteronomy 25:7-11). Granted, Onan lived before the Jewish Law was given, but if God did not think that failing to raise up children for one’s dead brother was a sin worthy of death for the Israelites after the Law was given, he probably did not think that way before it was given either. As a result, it’s unlikely that this was the reason why he killed Onan.

Next, let’s look at the second possibility. Did God punish Onan because he failed to continue the line of Judah? Again, not likely. While we know from the rest of Scripture how important that family tree would become, at this point in the story, there is not even a hint of it. The first indication in the Bible of Judah’s future importance comes later on, towards the end of Genesis (Genesis 49:8-12), so it would not be fair for God to expect Onan to understand that at this point. As a result, it is unlikely that this was the reason why Onan was put to death.

The Right Answer

At this point, we might be tempted to say that the third answer (that Onan’s sin was using an ancient method of contraception) has to be right simply by process of elimination, but let’s dig a bit deeper. Let’s see if there is any evidence supporting this option other than the failure of the other two alternatives. Specifically, take a look at these passages from the book of Leviticus:

“If a man has sexual relations with a man as one does with a woman, both of them have done what is detestable. They are to be put to death; their blood will be on their own heads.” (Leviticus 20:13)

“If a man has sexual relations with an animal, he is to be put to death, and you must kill the animal. If a woman approaches an animal to have sexual relations with it, kill both the woman and the animal. They are to be put to death; their blood will be on their own heads.” (Leviticus 20:15-16)

At first, it might be tough to see just what these passages have to do with the story of Onan, but let’s ponder them a bit. In these texts, God is prescribing death as the penalty for homosexual activity and bestiality, two acts that share something in common with contraception: all three of them are non-procreative forms of sexual activity. Sex with an animal or with someone of the same gender is intrinsically incapable of producing a child, and contraception artificially removes the procreative potential of the act.

Once we recognize that similarity, we can see that the third possible explanation for Onan’s punishment is most likely the right one. God didn’t think that failing to raise up children for one’s dead brother merited death for his ancient people, but he apparently thought that non-procreative forms of sex did, so Onan’s fate makes perfect sense. God killed him because he spilled his seed on the ground, thereby removing the procreative potential of his sex with his sister-in-law and making it similar in that key respect (but, we should note, not necessarily in any others) to homosexuality and bestiality, two sins that merited death in the Old Testament era.

Scriptural Support

Like I said before, this approach to the issue of contraception is particularly helpful when talking to other Christians. The story of Onan complements the philosophical arguments we normally use by confirming that our philosophy is in fact correct.  It shows us that the Church’s teaching on the matter is supported by both reason and revelation, so if a fellow Christian is having a tough time understanding or accepting the philosophy behind it, the fact that Onan was punished for rendering his sex non-procreative can help them see that the teaching is true even if they cannot fully see why it’s true.


JP Nunez has been a theology nerd since high school. He has master's degrees in both theology and philosophy (with a concentration in bioethics) from Franciscan University of Steubenville, and he spent three years in Catholic University of America's doctoral program in biblical studies before realizing that academia isn't where he wants to be. During his time in Steubenville, he worked for two years as an intern at the St. Paul Center for Biblical Theology, where his responsibilities included answering theological questions and helping to format and edit their Journey Through Scripture Bible studies. He blogs at JP Nunez: Understanding the Faith Through Scripture.

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