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Does the very act of sex cause you to be married?

Does the very act of sex cause you to be married according to the Bible?


Several years ago I held the view that there’s no such thing as premarital sex because the very act of sex causes you to be married. Since then I’ve changed my opinion, largely because of your book The Revenge of Conscience. My problem now is that even though I’ve changed my opinion, I honestly don’t know how to refute my former scriptural argument. Can you show me how to do it? Here it is:

  1. Having sex is synonymous with becoming one flesh (1 Corinthians 6:16).
  2. Becoming one flesh is synonymous with being married (Matthew 19:3-6).
  3. Therefore, having sex is synonymous with being married.

Thanks again for your help.


Yes, I think I can help you out. Here’s how I would revise your first two propositions to make them square with the biblical passages in question.

  1. Extramarital sex makes the man and woman one flesh (1 Corinthians 6:16).
  2. Marital sex also makes the man and woman one flesh (Matthew 19:3-6).

Follow closely here: It doesn’t follow from these two premises that extramarital sex makes two people married. If we draw that conclusion, we would commit the same logical fallacy as thinking “Campfires make warmth, and sunlight makes warmth, so campfires must make sunlight.”

If you don’t mind my throwing in a little bit about natural law, let me add what I think the Bible means when it says that the sexual act makes the two people one flesh. Short of a divine provision for people called to permanent singleness, there is something missing in the man which must be provided by the woman, and something missing in the woman which must be provided by the man. This is most obvious in the physical dimension. In the case of all other biological functions, only one body is required to do the job. A person can digest food by himself, using no other gullet but his own; he can see by himself, using no other eyes but his own; he can walk by himself, using no other legs but his own; and so on with each of the other functions and their corresponding organs. Each of us can perform every vital function by himself, except one. That one is procreation.

What this demonstrates is that among human beings the male and female sexual powers are radically incomplete, and designed for each other. If we were speaking of respiration, it would be as though the man had the diaphragm, the woman the lungs, and they had to come together to take a single breath. If we were speaking of circulation, it would be as though the man had the right heart chambers, the woman the left, and they had to come together to make a single beat. Now it isn’t really like that with the respiratory or circulatory powers, but that is exactly how it is with the generative powers. The union of opposites is the only possible realization of their procreative potential; unless they come together as a single organism, as “one flesh,” the procreative act has not taken place.

That’s what one-flesh unity means. But marriage is more than one-flesh unity; it’s what sanctifies one-flesh unity. The act of marriage is the entrance into a divinely blessed and covenantally-sealed procreative partnership.

Does that help? By the way, I’m glad that The Revenge of Conscience was useful to you. You might want to check out my new book What We Can’t Not Know.

Grace and pace,


Copyright 2004 Professor Theophilus. All rights reserved.

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About the Author

J. Budziszewski

Professor J. Budziszewski is the author of more than a dozen books, including How to Stay Christian in College, Ask Me Anything, Ask Me Anything 2, What We Can’t Not Know: A Guide, and The Line Through the Heart. He teaches government and philosophy at the University of Texas, Austin.

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