A friend asked recently how I would respond to someone that believes the Catholic Church teaches that sex is sinful. This post is a general response to that question. I know that there were other specific things relating to the discussion with her friend, but I wanted to keep my response here to that basic question.
My first thought in such cases is that in order to have any kind of rational discourse, you must be able to get the other person to agree as to WHAT Church authority they will consider the proper teaching authority of the Church. It must be something beyond "the nuns who taught me sex ed in Catholic school 30 years ago" or "everybody knows that". Ideally, if you can get them to agree that the Catechism of the Catholic Church contains the 'rules' which govern Catholic life, you're golden. That may take a discussion or several, but it really does have to be the starting point to get beyond the "he said, she said" sort of arguments. If they are of the 'my opinion of what your Church teaches is just as valid as your opinion' mindset, and will not agree that there can be a definitive source of teaching, then there's no way to have a rational conversation on the subject and further discussion will only devolve into argument.
For the specific challenge of the Catholic Church teaching that sex is sinful I counter, no, the Church teaches that sex is SACRED and therefore not something to be taken lightly or entered into frivolously.
From the CCC (Catechism of the Catholic Church):
III. THE LOVE OF HUSBAND AND WIFE
2360 Sexuality is ordered to the conjugal love of man and woman. In marriage the physical intimacy of the spouses becomes a sign and pledge of spiritual communion. Marriage bonds between baptized persons are sanctified by the sacrament.
2361 "Sexuality, by means of which man and woman give themselves to one another through the acts which are proper and exclusive to spouses, is not something simply biological, but concerns the innermost being of the human person as such. It is realized in a truly human way only if it is an integral part of the love by which a man and woman commit themselves totally to one another until death."
Tobias got out of bed and said to Sarah, "Sister, get up, and let us pray and implore our Lord that he grant us mercy and safety." So she got up, and they began to pray and implore that they might be kept safe. Tobias began by saying, "Blessed are you, O God of our fathers. . . . You made Adam, and for him you made his wife Eve as a helper and support. From the two of them the race of mankind has sprung. You said, 'It is not good that the man should be alone; let us make a helper for him like himself.' I now am taking this kinswoman of mine, not because of lust, but with sincerity. Grant that she and I may find mercy and that we may grow old together." And they both said, "Amen, Amen." Then they went to sleep for the night.
2362 "The acts in marriage by which the intimate and chaste union of the spouses takes place are noble and honorable; the truly human performance of these acts fosters the self-giving they signify and enriches the spouses in joy and gratitude." Sexuality is a source of joy and pleasure:
The Creator himself . . . established that in the [generative] function, spouses should experience pleasure and enjoyment of body and spirit. Therefore, the spouses do nothing evil in seeking this pleasure and enjoyment. They accept what the Creator has intended for them. At the same time, spouses should know how to keep themselves within the limits of just moderation.
2363 The spouses' union achieves the twofold end of marriage: the good of the spouses themselves and the transmission of life. These two meanings or values of marriage cannot be separated without altering the couple's spiritual life and compromising the goods of marriage and the future of the family.
The conjugal love of man and woman thus stands under the twofold obligation of fidelity and fecundity.
How cool is that?! The Church teaches that sex within marriage was created for both the pleasure of the spouses and the transmission of life. Clearly not teaching that sex is sinful.
You would be correct in saying that the Church limits the beautiful and sacred act of sex to those within bonds of holy matrimony. If you have issues with that limitation, we can discuss that another time, but it is the clear teaching of the Church that sex is a GOOD thing, not a sinful act.
A couple of good resources for some one who wants to know more about the Catholic views on sex are:
The Theology of the Body website- a great place to start!
The Theology of the Body Institute website
Good News about Sex and Marriage by Christopher West