We are bodily and spiritual beings. These are two distinct dimensions of who we are, but they always show up together. It's striking if you stop to think about it: spiritual realities like sadness or joy express themselves through physical things like tears and facial expressions; and physical pain can leave you feeling like life has lost its meaning. Human sexuality belongs to this body-and-soul way of being. For a human being, sex is never merely physical. It's spiritual too, and bringing both dimensions together takes real, ongoing effort.

The sixth commandment is sometimes phrased as "you shall not commit adultery," sometimes as "you shall not commit impure acts." Either way, it's about human sexuality as a whole — sex, love, marriage, family, and celibacy — and it tells us not to use our sexuality against the purposes the Creator built into it: procreation and the union of marriage.

Like every other commandment, this one is really an invitation to love, and, properly understood, it's a joy rather than a burden. It calls us to love God first, and then to love other people as whole persons, body and soul together. That means never loving just someone's soul, or just their body, but the whole person. Sexuality is one of God's gifts to us, a way of sharing in his power to create life, and it only makes sense within his larger plan for us. Jesus confirms this when He says, "Blessed are the pure in heart, for they will see God" (Mt 5:8).

Integrating our sexuality

Today, more than ever before, it's easy to find information about sex and how a sexual relationship works physically and biologically. What's harder to find (or what people are less interested in) is its human meaning. Understanding that meaning requires having real convictions about who man and woman are, and about the love that can exist between them.

Here's an analogy: we can know that our lungs let us breathe, oxygenate our blood, and keep our organs alive, but having that information isn't the same as understanding what life is for. In the same way, we can know the biological function of our sexual organs without knowing their deeper, spiritual purpose. That purpose is love, so living out this commandment means loving the way God loves: giving ourselves to another person as an exclusive gift, generating new life through procreation (sharing, in a small way, in God's own creative power), and uniting the whole person, body and soul.

Integrating sexuality into who we are means working toward self-mastery. With that self-mastery, sexuality can become something truly personal and human; something lived out as an act of self-giving and love between a man and a woman.

Living out the commandment

Experience shows all of us carry the effects of original sin, which means we feel a pull toward evil and toward distorting our own nature. That's why this commandment asks us to guard our capacity to love, so that these disordered tendencies can be brought up to the high place God intended for them.

Lust is the vice opposed to chastity; the disordered enjoyment of sexual pleasure, pursued apart from its true purpose. The Catechism lists the sins against chastity this way: masturbation, fornication, adultery, pornography, and prostitution. These are usually preceded by impure desire, about which Jesus says: "Everyone who looks at a woman with lust has already committed adultery with her in his heart" (Mt 5:28). Underneath these sins lies a frustrated desire for real communication with another person. It's a longing for connection that ends up cut short.

Sexuality and marriage

Sexuality reaches its full and proper meaning, in all its dimensions — bodily, emotional, and spiritual — in the love between husband and wife, according to the Creator's plan. That plan is already revealed in Genesis, in the striking phrase "one flesh," and Jesus reaffirms it when He speaks about the indissolubility of marriage (cf. Mt 19:6). The sexual relationship between spouses goes far beyond the merely physical, because it involves the whole person — yet the Creator has also given it a physical pleasure and joy that, by its origin and purpose, is good and holy.

For this reason, marriage requires fidelity; it calls for a lifelong commitment. Today, sex is often thought of as something separate from love, something whose whole point is individual pleasure. Christianity teaches something different: it's the commitment of love that makes sex joyful, not enjoyable sex that makes commitment last.

Adultery is what opposes this fidelity: a sexual relationship between a married person and someone other than their spouse. It violates the other spouse's exclusive rights and strikes at the institution of marriage itself. But faithfulness between spouses is about far more than not cheating in this way: it's a mutual and exclusive gift of self, body and soul, that takes in the senses, the mind, and the heart.

As the body ages and sexual passion and romance naturally fade, it might seem like married love should fade with them. But married love is so much more than sexual gratification and romantic feeling that it's actually meant to grow into something fuller and deeper: a higher kind of love, bound up more with self-giving, self-denial, generosity, and sacrifice. This is the maturity of love, the very thing that gives it solidity and lasting stability.