Marriage and civil societies.
The very fact that this marriage is going to the Supreme Court is a sad reflection on a free and civil society. Homosexuals make up only 1.6% of the population, and only about 25% want to be married. Why should a mere 0.4% of the population have the right to dictate to the rest of us what morality and marriage is?
Too many people confuse Law with Culture. A civil society makes laws in order to keep it vibrant and sustainable. All states have laws for helping married couples and to make help women who spend their time raising children and not working. Families get tax benefits and survivor benefits, that are NOT needed for same sex partners, because they will not create offspring that are related to both partners.
Traditional marriage has been around since before Christianity, all societies recognizes the need for it, even Atheists get married.
A civil society has the right to Promote, Permit, or Prohibit anything that would lead to it destruction or loss of viability.
Traditional Marriage of a man and woman is Promoted in order to keep the civil society alive by creating stable families. It Permits civil unions as an act of kindness to those in non-traditional relationships, and to give some rights that seem to be needed. However, the civil society also Prohibits anything that attacks, lessens, or destroys what it Promotes like traditional marriage.
Society need stable nurturing families of a Man and Woman to help them raise children, for without stable families a civil society will not exist.