For years countless heroes, Catholic and not, sung and unsung, have labored courageously to save the institution of marriage from the onslaught of those who seek to redefine it. Behind this vociferous public attack from without, marriage is struggling against another, more insidious attack that threatens its continued existence from within: cohabitation. Unlike same-sex unions, which are visibly and obviously different from natural marriage, cohabitation shares many of the trappings of marriage: chores, bills, sex, and even children. The similarities have enticed many prospective brides and grooms to try cohabitation first: according to Our Sunday Visitor, today more than half of first marriages begin with cohabitation, which has led to a 1100 percent increase in cohabitation nationally since 1970.
But cohabitation is not marriage, and it is not a sacrament. The difference lies in the essence and purpose of each. Cohabitation is an at-will agreement to share a roof and a bed for as long as both parties are satisfied. Unlike traditional marriage, which requires legal registry and witnesses because of its public dimension, cohabitation is a private affair. While marriage publicly declares that two individuals have united to raise children for the common good, cohabitation, in the analysis  of Prof. Robert George, values sex as an instrumental good – as a means to some other good for two individuals who remain autonomous in every way except their address. Due to the prevalence and tacit acceptance of cohabitation today, many couples who enter into this state do not have malicious intent; some do not even suspect that it is wrong. Nevertheless, the decision to cohabitate says that one has placed himself or herself and his or her sexual desires ahead of everyone and everything else, including the cohabiting partner.
The sexual revolution has labored mightily to discredit, dismiss, and bury the Church’s understanding of marriage and sexuality, the final societal bulwark against complete sexual libertinism. The revolution has seduced Catholics as much as the general population. It is no secret that most Catholics continue to ignore the Church’s teaching against birth control, that more engaged couples are foregoing a Church wedding, and that many of those who are married in the Church have consummated their union long before they approach the altar. Against such realities, the Church can do little more than put forward her vision of marriage in the hope that it will be heard. Thoughtful reflection may well find the Church’s teaching refreshing – and compelling.
The Catechism of the Catholic Church describes marriage as a creation of a loving God who has called men and women to love as the fundamental purpose of their existence. Since men and women are created in the image and likeness of God, “their mutual love becomes an image of the absolute and unfailing love with which God loves man.” The union of husband and wife reflects the union of God with His people, and, in the analogy of St. Paul, the union of Christ the bridegroom with His bride, the Church.
Marriage, then, is a sacrament established by Christ, who enabled married couples to overcome the burden of original sin by personally granting the couple “the strength and grace to live marriage in the new dimension of the Reign of God” (CCC 1615). The grace of the sacrament unites a couple by virtue of their mutual consent in an indissoluble bond so that they may “help one another to attain holiness in their married life and in welcoming and educating their children” (1641). From the grace of the sacrament comes the capacity to love, to forgive, to comfort, to support, and to nurture each other on all occasions, in every season. Like the grace of baptism and confirmation, both newlyweds and golden jubilarians can call upon and strengthen the grace of marriage through prayer, through the sacraments of reconciliation and Eucharist, and through natural activities – from romantic dinners to painting the house – done in a spirit of mutual love and charity.
The sexual union of the spouses, intended for procreation and for strengthening the bond between them, is the physical expression of the essence of marriage: the complete gift of oneself to another. In their wedding vows, couples freely promise to love each completely, exclusively, and faithfully in hope that their marriage will bear the fruit of children. Christopher West, who has synthesized for popular audiences Pope John Paul II’s “theology of the body,” a profound meditation on the meaning of the complete gift of self in marital union, describes each sexual act of married couples as a renewal of wedding vows. For this reason the Church teaches that sex belongs only in marriage, for only then is the act free, total, faithful, and fruitful. This is also the reason for the Church’s condemnation of artificial birth control: it prevents, whether through physical or chemical means, the free and total giving of self that bears fruit in another human life.
The visions of sex and marriage offered by the Church and by cohabitation could not be more different. Pope John Paul II often said that the Church only proposes; she imposes nothing. We remain free to choose – or not – the revealed path to authentic love.