Those who want so-called “same-sex marriage” say they want “diversity”. But a same-sex relationship is about sameness which is the opposite of diversity. True diversity is the union of the opposite sexes in holy matrimony. Marriage is a foundational teaching of the Catholic Church. But men and women joining together for life for the sake of their children in natural marriage predates the Church and predates every government in human history. The union of one man and one woman in natural marriage is in accordance with how the bodies of men and women are designed to fit together and produce babies. Without men and women getting together to make babies there would be no human race which means no governments, no bishops, no priests, no apostolic succession, no sacraments, no Church. Jesus defined marriage as being between one man and one woman when he said, “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’? So they are no longer two but one flesh. What therefore God has joined together, let not man put asunder.” - Matthew 19:4-6
“Gay” activists reject natural marriage but want their relationship to be called the same thing as what they reject. It makes no sense.
“Refusing to human life any sacred or spiritual character, such a doctrine logically makes of marriage and the family a purely artificial and civil institution, the outcome of a specific economic system. There exists no matrimonial bond of a juridico-moral nature that is not subject to the whim of the individual or of the collectivity. Naturally, therefore, the notion of an indissoluble marriage-tie is scouted. Communism is particularly characterized by the rejection of any link that binds woman to the family and the home, and her emancipation is proclaimed as a basic principle. She is withdrawn from the family and the care of her children, to be thrust instead into public life and collective production under the same conditions as man. The care of home and children then devolves upon the collectivity. Finally, the right of education is denied to parents, for it is conceived as the exclusive prerogative of the community, in whose name and by whose mandate alone parents may exercise this right.” - Divini Redemptoris, Encyclical of Pope Pius XI on Atheistic Communism