Leo XIII on what marriage owes to the Church

By Thomas V. Mirus ( bio - articles - email ) | Jan 02, 2026 | In Magisterium of Leo XIII

This is part of a series of articles and podcast episodes surveying the most important encyclicals of Pope Leo XIII.

The Church’s magisterium has devoted more attention to marriage in the modern era than in any previous time. This has been a response to the many moral and doctrinal challenges to marriage, but it also connects with the broader project of Catholic social teaching launched by Leo XIII, for marriage is the basis of the fundamental social unit, the family.

Leo began the new era of frequent papal teaching on marriage on February 10, 1880, with the publication of his fourth encyclical, Arcanum. It was, Russell Hittinger notes, “the first formal and synoptic teaching on marriage since the Council of Trent”—a gap of four centuries.

It is worth noting that Leo XIII’s Arcanum and Pius XI’s Casti Connubii, the latter written for the first encyclical’s fiftieth anniversary in 1930, are still the highest-level papal documents that have been devoted specifically to summarizing Church teaching on marriage. The only comparable document since then is John Paul II’s Familiaris Consortio, but it is broader in scope, dealing with the life of the family in society more generally.

Arcanum and Casti are distinct in their focus. Arcanum frames the subject mainly in terms of what the Church has done to uplift and protect marriage throughout history. Leo argues at length that the state has no right to usurp the Church’s governance of marriage. Casti Connubii, while building on the foundation laid by Leo, is even more expansive about marriage itself, its ends, and how it should be lived, from the point of view of the spouses.

In fact, if I were to recommend every Catholic read one Church document on marriage, it would easily be Casti Connubii (you can listen to our free audiobook of it). I love it because it is both old enough to reiterate aspects of marriage that modern Church leaders typically avoid discussing, and recent enough to explain them in a way that is sensitive to modern concerns.

But here my focus will be on Arcanum, which is foundational, unique, and well worth reading in its own right.

Christ renewed marriage

The essential point of Arcanum is that Christ and His Church are the great benefactors of marriage, not only in its supernatural dimension, but even in strengthening and protecting it as a natural institution.

From the creation of Eve out of the side of Adam, it is evident that God intended marriage to have the two marks of unity and perpetuity. Jesus confirmed the divine law that marriage is between one man and one woman in a one-flesh union which can never be dissolved by the will of human beings.

In between Adam and Christ, marriage was gradually corrupted, even among the Jews (the allowance of divorce), but far more among the pagan nations. Leo’s summary of the pagan corruption of marriage is worth quoting in full:

All nations seem, more or less, to have forgotten the true notion and origin of marriage; and thus everywhere laws were enacted with reference to marriage, prompted to all appearance by State reasons, but not such as nature required. Solemn rites, invented at will of the law-givers, brought about that women should, as might be, bear either the honorable name of wife or the disgraceful name of concubine; and things came to such a pitch that permission to marry, or the refusal of the permission, depended on the will of the heads of the State, whose laws were greatly against equity or even to the highest degree unjust. Moreover, plurality of wives and husbands, as well as divorce, caused the nuptial bond to be relaxed exceedingly. Hence, too, sprang up the greatest confusion as to the mutual rights and duties of husbands and wives, inasmuch as a man assumed right of dominion over his wife, ordering her to go about her business, often without any just cause; while he was himself at liberty ‘to run headlong with impunity into lust, unbridled and unrestrained, in houses of ill-fame and amongst his female slaves, as if the dignity of the persons sinned with, and not the will of the sinner, made the guilt.’ [Here he is quoting St. Jerome.] When the licentiousness of a husband thus showed itself, nothing could be more piteous than the wife, sunk so low as to be all but reckoned as a means for the gratification of passion, or for the production of offspring. Without any feeling of shame, marriageable girls were bought and sold, like so much merchandise, and power was sometimes given to the father and to the husband to inflict capital punishment on the wife. Of necessity, the offspring of such marriages as these were either reckoned among the stock in trade of the common-wealth or held to be the property of the father of the family; and the law permitted him to make and unmake the marriages of his children at his mere will, and even to exercise against them the monstrous power of life and death.

(Some of Leo’s teachings will challenge feminists, but the above also challenges those who, under the guise of true masculinity, promote the pagan rather than the Christian form of patriarchy.)

But Christ came to renew all things in Himself, reminding us of God’s original plan for marriage. The Apostles, handing down His teaching, more fully explained the doctrine of Christian marriage, with St. Paul revealing that it is a type of the union between Christ and the Church. This union now had an even higher purpose than the natural propagation of the human race: to bring forth souls to inherit God’s eternal kingdom.

The Apostles laid out the duties and rights of husband and wife, as summarized by Leo:

They are bound, namely, to have such feelings for one another as to cherish always very great mutual love, to be ever faithful to their marriage vow, and to give one another an unfailing and unselfish help. The husband is the chief of the family and the head of the wife. The woman, because she is flesh of his flesh, and bone of his bone, must be subject to her husband and obey him; not, indeed, as a servant, but as a companion, so that her obedience shall be wanting in neither honor nor dignity. Since the husband represents Christ, and since the wife represents the Church, let there always be, both in him who commands and in her who obeys, a heaven-born love guiding both in their respective duties.

Who governs marriage?

Christ entrusted the care and discipline of marriage to His Church. Throughout Arcanum, Leo gives numerous historical examples from the Apostles onward of the Church defending the indissolubility of marriage, correcting immorality, and opposing heresies and civil laws that were contrary to the nature of marriage.

In particular, the Church’s laws gave a much greater equity to marriage. She abolished the distinction which prevented intermarriage between slaves and free. She taught that the rights of husbands and wives are equal in regard to fidelity, mutual affection, and marital duties; she asserted the dignity of the woman; she abolished the double standard with regard to adultery; she forbade incest and took care to ensure the validity of unions.

We all know that the very nature of marriage has been under attack in modernity. But one thing we have gotten more used to, which Leo condemned in his time, is the denial of the Church’s jurisdiction over marriage. Men sought to bring marriage completely under the regulation of the civil authority and remove it from the Church’s authority, chiefly by the creation of so-called “civil marriage.”

This is one area where it seems there is no way of having just laws without explicit recognition of the authority of the Church. Otherwise, the conflict is inevitable because the civil power will try to dissolve marriages that the Church says cannot be dissolved. Thus marriage (alongside education) is one of the chief areas in which Catholic social teaching insisted on the rights of the Church.

Leo makes the fascinating point that there is something innately religious about marriage, as was generally recognized by the pagans. It was inherently sacred as an institution made by God, even before it was a Christian sacrament. Since civil rulers have no right to regulate the sacred, only the Church has authority over marriage as such. And of course, this becomes even more obvious when we are talking about sacramental marriage between Christians.

But couldn’t the natural or civil aspects of marriage be distinguished from the sacrament, so that the state has authority over the former and the Church over the latter? Leo strongly denies that the sacrament is an “added ornament” which can be separated from the contract:

...in Christian marriage the contract is inseparable from the sacrament, and that, for this reason, the contract cannot be true and legitimate without being a sacrament as well. For Christ our Lord added to marriage the dignity of a sacrament; but marriage is the contract itself, whenever that contract is lawfully concluded.

For me, this raises a troubling question about the way annulment cases are handled in the U.S.A. Diocesan tribunals generally either require or expect that the spouses will have secured a civil divorce before seeking an annulment. But there is a seeming conflict here: the Church presumes marriages are valid unless proven otherwise. Therefore it seems that she should be discouraging couples from getting a civil divorce—the very existence of which Leo says is an affront to the Church’s authority over marriage—while the Church still presumes the validity of their marriage, and an investigation has not even taken place yet.

The evils of divorce

Speaking of divorce, it is to this that Leo turns next. Listing the many good social fruits of marriage, he says that the institution of marriage will lose these benefits when detached from the Church. Spouses will become enslaved to vicious passions and overwhelmed by the duties of marriage, and thus they will desire to be set free of their vows and to change the laws in order to do so.

Leo warns from historical precedent that when divorce begins to be tolerated to any degree, its use cannot long be restrained within any bounds, for its very possibility makes people desire it. Consider: A man who goes into marriage with the theoretical understanding that marriages can be dissolved can still have a valid marriage so long as he personally intends never to get divorced. But the mere idea that divorce is possible will make him more likely to betray his original intent when things get difficult.

Thus it is not only the actual instance of divorce, but its very conceivability that brings about great social evils:

Matrimonial contracts are by it made variable; mutual kindness is weakened; deplorable inducements to unfaithfulness are supplied; harm is done to the education and training of children; occasion is afforded for the breaking up of homes; the seeds of dissension are sown among families; the dignity of womanhood is lessened and brought low, and women run the risk of being deserted after having ministered to the pleasures of men.

And so, Leo calls for harmonious relations between states and the Church with regard to the regulation of marriage. He insists that two Christians who enter a non-sacramental “civil marriage” are not married at all. He also clarifies that the civil law can regulate secular matters that are downstream of marriage (you might think of matters regarding inheritance, household finances and such), but these matters are dependent on the fact of there being a valid marriage in the first place—which only the Church can judge.

Finally, Leo says, spouses would find the burdens of their state much more bearable if they drew their strength from religion alone. For this reason, he warns strongly against mixed marriage:

Care also must be taken that they do not easily enter into marriage with those who are not Catholics; for, when minds do not agree as to the observances of religion, it is scarcely possible to hope for agreement in other things. Other reasons also proving that persons should turn with dread from such marriages are chiefly these: that they give occasion to forbidden association and communion in religious matters; endanger the faith of the Catholic partner; are a hindrance to the proper education of the children; and often lead to a mixing up of truth and falsehood, and to the belief that all religions are equally good.

For a more thorough discussion of Arcanum, listen to the corresponding episode on the Catholic Culture Podcast: