At Mass this Sunday we heard from St. Paul:
Brothers and sisters: Be subordinate to one another out of reverence for Christ. Wives should be subordinate to their husbands as to the Lord. For the husband is head of his wife just as Christ is head of the church, he himself the savior of the body. As the church is subordinate to Christ, so wives should be subordinate to their husbands in everything. Husbands, love your wives, even as Christ loved the church and handed himself over for her to sanctify her, cleansing her by the bath of water with the word, that he might present to himself the church in splendor, without spot or wrinkle or any such thing, that she might be holy and without blemish. So also husbands should love their wives as their own bodies. He who loves his wife loves himself. For no one hates his own flesh but rather nourishes and cherishes it, even as Christ does the church, because we are members of his body.
For this reason a man shall leave his father and his mother
and be joined to his wife,
and the two shall become one flesh.
This is a great mystery, but I speak in reference to Christ and the church.
(Eph 5:21-32)
This passage, the last line in particular, is key to understanding what the Church teaches about sex and marriage. For Catholics, marriage is not just some contract between two people who agree to love each other for life and maybe have a couple of kids. It is a sacrament and a symbol that expresses an eternal reality.
Throughout the Old Testament God’s love for His people is expressed in terms of the love of a bridegroom for His bride (see Is. 62:4-5 for example). And in the book of Revelation (19:7) we hear of the marriage of the Lamb (Christ) to His bride (the Church). The central point of the Theology of the Body is that the body has a language – it speaks – and it is meant to proclaim the “spousal” love of Christ and the Church. And this, St. Paul is telling us, is nowhere more apparent than in the intimate “one flesh union” of husband and wife. Why? To use the words of Christopher West:
In order to be “true to the sign,” the spouses must speak as Christ speaks. Christ gives his body freely (”No one takes my life from me, I lay it down of my own accord,” Jn 10:18). He gives his body without reservation (”he loved them to the last,” Jn 13:1). He gives his body faithfully (”I am with you always,” Mt 28:20). And he gives his body fruitfully (”I came that they may have life,” Jn 10:10).
This is the love a couple commits to in marriage. Standing at the altar, the priest or deacon asks them: “Have you come here freely and without reservation to give yourselves to each other in marriage? Do you promise to be faithful until death? Do you promise to receive children lovingly from God?” Then, having committed to loving as Christ loves, the couple is meant to incarnate that love in sexual intercourse. In other words, sexual union is meant to be where the words of the wedding vows “become flesh.”
Any sexual act outside of this context is a gross distortion of the eternal reality it is meant to symbolize. Pre-marital sex lacks the faithful commitment of the man and woman, extra-marital affairs break that commitment and same-sex intercourse will never, under any circumstances, be fruitful. Likewise contraception disrupts both the fruitfulness of the marital embrace and, by withholding one’s fertility from the act, is a violation of the total self-gift that spousal intimacy is meant to be.