Until a "lack of discretion" do us part.

Ever since the church got involved in the wedding ceremony, relatively late in Christian history, it has stood by its main belief about a marriage: It's the consent of the couple that binds.

After 12 years of marriage, Sheila Rauch Kennedy and U.S. Rep. Joseph P. Kennedy II obtained a civil divorce. Two years later, in 1993, Joe sought an annulment of the marriage so he could wed longtime aide Beth Kelly and remain in good standing with the Catholic Church--de rigueur for a Kennedy preparing to run for governor of Massachusetts.

Understanding correctly that an annulment would signify that their marriage had never been valid, Sheila refused to cooperate. She also refused to let the matter pass in silence. In Shattered Faith: A Woman's Struggle to Stop the Catholic Church from Annulling Her Marriage (Pantheon, 1997), the former Mrs. Kennedy reported Joe's enraged reaction to her refusal to agree that a sacramental marriage had never existed. "Nobody actually believes it," he exclaimed. "It's just Catholic gobbledygook, Sheila."

The distinction between a divorce, which ends a marriage, and an annulment, which denies one ever existed, may indeed be gobbledygook. But it is our gobbledygook, and it developed over centuries of theological reflection on the grace-filled experience of Christian marriage.

In the broad sense, church historian Joseph Martos explains, marriage was regarded as a sacrament relatively early in the Christian experience. But it was not until the 12th century that it came to be seen as an official sacrament.

For much of the first Christian millennium, the imperial state regulated marriage (and thorny questions such as divorce), while the church was content to recognize and sometimes celebrate the holiness of marriage, if not sexual intercourse. There were, however, inevitable tensions between civil society's and Christian ideals of marriage.

Jesus strongly prohibited divorce and remarriage, for example, and Saint Paul praised the fidelity between man and woman as a symbol and enactment of Christ's love for his church. Jesus' insistence on the indissolubility of a union "which God has joined" was taken as the moral norm in the early church. But Matthew's formulation of this teaching left the door open for exceptions to the ban on divorce and remarriage: "The man who divorces his wife--I am not speaking of porneia--and marries another, is guilty of adultery" (Matt. 19:6). Initially translated as "fornication," porneia was later expanded to include not only infidelity but robbery, kidnapping, treason, and other forms of gross immorality.

Bishops in some places allowed divorce and remarriage under certain conditions. Christians married according to the civil laws of the time, in a family ceremony, and often without any special church blessing.

In 866 Pope Nicholas I declared that a marriage was legal and binding even without any public or liturgical ceremony. "If anyone's marriage is in question, all that is needed is that they gave their consent, as the law demands," he wrote. "If this consent is lacking in a marriage then all the other celebrations count for nothing, even if intercourse has occurred." This church teaching of the primacy of the couple's consent has remained consistent to the present day.

In the East, liturgical weddings, performed in churches, became common by the eighth century. In the West, however, the tradition of marriage as sacrament, elaborated by Saint Augustine in the fifth century, remained largely forgotten. To Augustine, marriage was a visible union between Christ and his spouse, the church, as well as a sacred pledge of fidelity bonding husband and wife. Like the sacrament of Baptism, it was permanent. Hence, "the marriage bond is dissolved only by the death of one of the partners." Even after the pledge of fidelity was broken by adultery, he reasoned, the couple remained joined by the invisible sign of their union in Christ.

Centuries later, Augustine's ideas would be retrieved at the moment when social circumstances required the church to declare its abiding conviction that marriage, properly understood and freely entered, constitutes a lifetime bond.

That moment came in the 9th and 10th centuries as ecclesiastical courts throughout Europe gained exclusive jurisdiction over marriage and divorce cases. The liturgical development of marriage followed. Bishops invoked previous papal teaching--including a series of forged decretals!--to define a legal wedding as one presided over by a priest and observed by two witnesses. Gradually the wedding ceremony, performed at the church door, was followed by a nuptial Mass inside the church. Although the ceremony now came to be conducted by the clergy, Pope Alexander III (1159-81) reaffirmed that the bride and groom, by giving free consent to the marriage, were the actual ministers of the sacrament. The church alone, Alexander argued, could nullify or void this marriage contract, but only if competent church authorities determined that one or both partners had not given consent.

With the exception of the "Pauline privilege," by which non-Christian marriages could be dissolved if one of the spouses converted to Catholicism, henceforth the church would grant no divorces whatever.

The church, in short, has consistently taught that consent forms the bonds of marriage. Today, marriage tribunals determine whether certain conditions impeded the bride's or the groom's ability to give consent to the marriage. The internal constraints include, among others, "a lack of sufficient reason" (caused, for example, by drug use, mental incompetency, or psychological disorders) and "a grave lack of discretion." The latter condition is difficult to prove, or disprove--even with a Joe Kennedy, who was quite willing to be deemed gravely lacking in discretion.

Annulments strike many Catholics as a morally dishonest loophole. The perception that they have become a Catholic version of divorce does not help. Only 338 annulments were granted in America in 1968. Today, the annulment figure is around 60,000, and more than 80 percent of those seeking annulments obtain them. Even the pope has publicly stated that the process in the U.S. is "too easy and hurried."

The possible abuse of the annulment procedure notwithstanding, American Catholics would do well to consider the wisdom of the church's theology of marriage. The decision to declare the vast majority of marriages "sacramental," and therefore indissoluble, has rested on firm theological ground--the belief that Christian marriage is one of Christ's primary means of transforming selfish and sinful human beings into self-sacrificing lovers formed in the image of the Holy Trinity. It is, in short, a vessel of saving grace.

So powerful a witness to holiness borne of patience and fidelity was marriage that the church (led for the most part by the non-married, at least after 1123) overcame its centuries-old suspicion of sexual intercourse as an inherently self-indulgent act. Throughout the early Middle Ages most churchmen held virginity in higher esteem than marriage; even intercourse motivated by the desire for children was deemed impure. But the rise of the Albigensian sect in southern France forced theologians to reconsider the positive good of sexuality. The misguided Albigensians taught that matter was evil and rejected marriage altogether because it brought new material beings into the world. Extreme views held by one's sworn enemies have a way of clearing the mind of murky thinking.

Developments in the 20th century both deepened and broadened the understanding of the sacramentality and indissolubility of marriage, even as cultural understandings of its nature and function changed. Influenced by developments in psychology and the philosophy of personalism, Catholic thinkers reappraised the traditional teaching that marriage was primarily for the procreation and education of children. Theologians acknowledged that marriage and sex had meaning in themselves--the personal fulfillment and mutual spiritual growth of the spouses.

Vatican II did not reverse the traditional teaching but spoke of marriage as an intimate partnership, a union in love, a community, and a covenant. Love between spouses, the bishops confirmed, is "eminently human" and "involves the good of the whole person." Sexual relations within a Christian marriage "signify and promote that mutual self-giving by which spouses enrich each other with a joyful and thankful will."

Unfortunately, not all marriages achieve such mutual self-giving. The ones that do are considered sacramental. The ones that do not are considered marriages, to be sure, but dissolvable because not oriented in freedom to God's invitation, incarnated in one's spouse, to self-abandonment. Annulments are the church's attempt to recognize and honor the permanence of the sacramental bond, while exercising a kind of disciplined compassion for those who did not experience it and hope to try again. Gobbledygook? Perhaps.

By R. SCOTT APPLEBY, professor of history and director of the Cushwa Center for the Study of American Catholicism at the University of Notre Dame in Indiana.