Why Does the Church Teach That Marriage Is Between a Man and a Woman?

A Sensitive Question

Few Catholic teachings are as controversial today as the Church’s understanding of marriage. Many countries, including Australia since 2017, have legally recognised same-sex marriage. Many people, including many Catholics, see the Church’s position as out of step with modern values, and some have experienced it as hurtful.

This is a subject that touches people’s deepest relationships and identities, so it deserves to be discussed with care. Whatever one’s view, it is worth understanding what the Church actually teaches and why, rather than relying on caricatures.

Two Different Questions

The Church distinguishes clearly between two things:

Persons, who must always be treated with respect, compassion and love.
Marriage, which the Church holds has a particular nature, given by God and written into human nature.

Saying that marriage is between a man and a woman is a claim about what marriage is. It is not a judgement on the worth of any person.

What the Church Teaches About Persons

The Catechism states that people with same-sex attraction “must be accepted with respect, compassion, and sensitivity. Every sign of unjust discrimination in their regard should be avoided” (CCC 2358). Like every Christian, they are called to holiness, and they are full members of the Church.

The Church teaches that experiencing same-sex attraction is not in itself sinful. Her moral teaching concerns sexual acts, not feelings or identity. And she teaches that sexual activity belongs only within marriage for everyone. All unmarried Catholics, of any orientation, are called to chastity, as are married couples in their own way (CCC 2348–2350).

What Marriage Is

The Church’s teaching on marriage is not mainly about same-sex relationships. It is a positive vision of what marriage is, from which the rest follows.

The Church teaches that marriage is a lifelong partnership between a man and a woman, “ordered by its nature to the good of the spouses and the procreation and education of offspring” (canon 1055; CCC 1601).

Marriage, on this view, has two inseparable purposes:

the union of the spouses, a total gift of self to one another in body and soul;
the procreation and raising of children.

The union of man and woman is uniquely the kind of union from which new human life naturally comes. Men and women are different and complementary, physically and in other ways. Their bodily union is the only kind of sexual union that is, by its nature, open to creating a new life who is the child of both. Marriage, as a social institution found in nearly every culture, grew up around this reality: to bind a man and a woman to each other and to any children they may have.

The Argument From Scripture

The Church points first to Scripture.

In Genesis, God creates humanity “male and female,” blesses them and says, “Be fruitful and multiply” (Genesis 1:27–28). He makes woman as a partner for man, and “a man leaves his father and his mother and cleaves to his wife, and they become one flesh” (Genesis 2:24).

When Jesus was asked about marriage, He went back to this beginning: “Have you not read that He who made them from the beginning made them male and female, and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’?” (Matthew 19:4–5).

Throughout the Bible, the union of husband and wife becomes an image of God’s covenant with His people and of Christ’s love for the Church (Ephesians 5:31–32).

The Argument From Reason

The Church also argues that this understanding of marriage is not only a religious belief. She holds that it can be known by reason, from human nature itself, through what is called natural law. (See What Is Natural Law?)

On this view, marriage is not simply a public recognition of any loving relationship between adults. It is a specific kind of union, defined by its connection to the bodily complementarity of man and woman and to children. Throughout history and across cultures, marriage has almost always been understood this way, by people of many religions and none.

Many people today reject this argument, holding that marriage is fundamentally about love and commitment between any two adults. Catholics who hold the Church’s view should understand that this is a genuine disagreement about what marriage is, held by many people of good will.

Blessings and Pastoral Care

In December 2023, the Dicastery for the Doctrine of the Faith published Fiducia Supplicans, which allowed priests to give short, spontaneous, non-liturgical blessings to people in irregular situations, including same-sex couples. It was careful to say that such blessings do not approve the relationship and do not resemble a wedding, and that the Church’s teaching on marriage is unchanged. The document was widely discussed and debated within the Church.

What it showed is the Church’s desire to reach out to every person with God’s love, while remaining faithful to her teaching.

A Hard Teaching

The Church acknowledges that her teaching asks a great deal of some people. For Catholics with same-sex attraction, it asks for a life of chastity that can be lonely and difficult. Many such Catholics live this teaching faithfully, and the Church calls her members to support them with real friendship and community, not just rules.

The Church’s teaching on marriage has also been used, at times, as an excuse for contempt and cruelty. That is a betrayal of the Gospel, which the Church condemns.

Truth and Love Together

The Church’s teaching on marriage cannot be separated from her teaching on the dignity of every person. Both come from the same conviction: that human beings are made in God’s image, male and female, and that God has a loving plan for every life.

Catholics are called to hold both together: to witness to the truth about marriage as the Church understands it, and to love every person without exception.