Pope Francis, Encyclical Lumen Fidei 52 The first setting in which faith enlightens the human city is the family. I think first and foremost of the stable union of man and woman in marriage. This union is born of their love, as a sign and presence of God’s own love, and of the acknowledgment and acceptance of the goodness of sexual differentiation, whereby spouses can become one flesh (cf. Gen 2:24) and are enabled to give birth to a new life, a manifestation of the Creator’s goodness, wisdom and loving plan.

Second Vatican Council, Pastoral Constitution Gaudium et spes 50

Marriage and conjugal love are by their nature ordained toward the begetting and educating of children.

The dignity of marriage and family, upon which the good of every society and the human race itself depends. This dignity excludes same-sex or other forms of “marriage” or sexual union which undermine the true nature of marriage and family, from which both children and the society of the future derives.

Pope Benedict XVI, Encyclical Caritas in Veritate 44

It is thus becoming a social and even economic necessity once more to hold up to future generations the beauty of marriage and the family, and the fact that these institutions correspond to the deepest needs and dignity of the person. In view of this, States are called to enact policies promoting the centrality and the integrity of the family founded on marriage between a man and a woman, the primary vital cell of society, and to assume responsibility for its economic and fiscal needs, while respecting its essentially relational character.

Pope Benedict XVI, Apostolic Exhortation Verbum Domini 85

[I]t must never be forgotten that the word of God is at the very origin of marriage (cf. Gen 2:24) and that Jesus himself made marriage one of the institutions of his Kingdom (cf. Mt 19:4-8), elevating to the dignity of a sacrament what was inscribed in human nature from the beginning. ‘In the celebration of the sacrament, a man and a woman speak a prophetic word of reciprocal self-giving, that of being one flesh, a sign of the mystery of the union of Christ with the Church (cf. Eph 5:31-32)’. Fidelity to God’s word leads us to point out that nowadays this institution is in many ways under attack from the current mentality. In the face of widespread confusion in the sphere of affectivity, and the rise of ways of thinking which trivialize the human body and sexual differentiation, the word of God re-affirms the original goodness of the human being, created as man and woman and called to a love which is faithful, reciprocal and fruitful."

Pope Francis, Apostolic Exhortation Amoris Laetitia 251

In discussing the dignity and mission of the family, the Synod Fathers observed that, ‘as for proposals to place unions between homosexual persons on the same level as marriage, there are absolutely no grounds for considering homosexual unions to be in any way similar or even remotely analogous to God’s plan for marriage and family.’ It is unacceptable ‘that local Churches should be subjected to pressure in this matter and that international bodies should make financial aid to poor countries dependent on the introduction of laws to establish marriage between persons of the same sex.’

United States Conference of Catholic Bishops, Forming Consciences for Faithful Citizenship 46

The human person is not only sacred but also social. Full human development takes place in relationship with others. The family—based on marriage between a man and a woman—is the first and fundamental unit of society and is a sanctuary for the creation and nurturing of children. It should be defended and strengthened, not redefined, undermined, or further distorted. Respect for the family should be reflected in every policy and program. It is important to uphold parents’ rights and responsibilities to care for their children, including the right to choose their children’s education.

Forming Consciences 70

The family founded upon marriage is the basic cell of human society. The role, responsibilities, and needs of families should be central national priorities. Marriage must be defined, recognized, and protected as a lifelong exclusive commitment between a man and a woman, and as the source of the next generation and the protective haven for children. The institution of marriage is undermined by the ideology of ‘gender’ that dismisses sexual difference and the complementarity of the sexes and falsely presents ‘gender’ as nothing more than a social construct or psychological reality, which a person may choose at variance with his or her biological reality (see Compendium of the Social Doctrine of the Church, no. 224). As Pope Francis has taught, ‘the removal of [sexual] difference creates a problem, not a solution’ (General Audience, April 22, 2015). ‘Thus the Church reaffirms . . . her "no" to gender philosophies, because the reciprocity between male and female is an expression of the beauty of nature willed by the Creator’ (Pope Benedict XVI, Address to the Pontifical Council Cor Unum, Jan. 19, 2013). This affirmation in no way compromises the Church’s opposition to unjust discrimination against those who experience ‘deep-seated homosexual tendencies,’ who ‘must be accepted with respect, compassion, and sensitivity’ (Catechism of the Catholic Church, no. 2358)."

Forming Consciences 71

Pope Francis has stressed, "Children have a right to grow up in a family with a father and a mother capable of creating a suitable environment for the child’s development and emotional maturity" (Address on the Complementarity Between Man and Woman, Nov. 17, 2014). Children who may be placed in foster care or with adoptive parents have a right to be placed in homes with a married man and woman, or if not possible, in environments that do not contradict the authentic meaning of marriage.

Forming Consciences 82

Parents—the first and most important educators—have a fundamental right to choose the education best suited to the needs of their children, including public, private, and religious schools.