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.
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.