CORPUS CHRISTI, TX (Catholic Online) - If society is visualized as a body, then the family is its vital cell.  It is the first natural society, the smallest indivisible unit of society, and is at the center of all social life.  It is a marvelous society, one formed by the communion of two human persons in the bond of marriage. 

Marriage is a permanent union between a man and a woman, persons equal in dignity, yet each with a personhood distinct and complementary.  Indeed, it is this complementarity that yields the great fruit of procreation, an office "which makes [the spouses] co-workers with the Creator." (Compendium, No. 209)

Though the family is a natural society, and though it is established through the "free choice of the spouses to unite themselves in marriage," the basic form of the family is not one that can be redefined by man.  This is because marriage which is the family's foundation is an "institution that does not depend upon man but on God himself." (Compendium, No. 215) 

"For God himself is the author of marriage and has endowed it with various benefits and purposes." (Compendium, No.215) (quoting Vatican II, Gaudium et spes, 48)   What God has written, no man ought to unwrite or rewrite.

The institution of marriage might be defined as an "intimate partnership of life and love . . . established by the Creator and endowed with him with its own proper laws." (Compendium, No.215) (quoting Vatican II, Gaudium et spes, 48)  The institution of marriage, its form, and its laws, are therefore not something that is the result of "human conventions or legislative prescriptions." 

We tamper with it at our peril.  It is a gift given, not a gift we make for ourselves.  It is something that exists in the what is, the order of reality, not something that exists in what we want it to be, the order of our own wills.

"Marriage is in fact endowed with its own proper, innate, and permanent characteristics." (Compendium, No. 216)  These exist regardless of our personal desires, personal whims and caprices, or disordered wishes.  They are part of what is.  If we ignore them, we live in the shadows of what Cardinal Newman called the "unreal."  While to be sure culture and societies may color marriage with different customs, at its center, marriage-which has a dignity and objective order of its own-remains unchanged." 

"This intrinsic dignity of marriage must be respected and safeguarded.  In fact, society is not at liberty "freely [to] legislate with regard to the marriage bond by which the two spouses promise each other fidelity, assistance, and acceptance of children."  Rather, society is "authorized [only] to regulate its civil effects." (Compendium, No.216)

The characteristic traits of marriage are four: totality, unity, indissolubility and fidelity, and fruitfulness, but they are all interrelated.

-totality: nothing is held back in the mutual spousal self-giving.
-unity: the result of the spousal self-giving, which, in biblical language is expressed as the spouses become "one flesh." (Gen. 2:24)
-indissolubility and fidelity: this characteristic comes from the total, permanent, and unique bond of marriage.
-fruitfulness: the spouses are open to new life, as it is at the heart of their self-giving as expressed in the self-giving conjugal act. "In its 'objective' truth, marriage is ordered to the procreation and education of children."
"Nonetheless, marriage was not instituted for the sole reason of procreation."  It therefore retains its other characteristics even if "children, although greatly desired, do not arrive to complete conjugal life." (Compendium, No 218-19)

As Catholics, we talk about the four "marks" of the Church--unity, holiness, catholicity, and apostolicity.  Without these, there is no authentic Church.  There are likewise four "marks" of marriage--totality, unity, indissolubility and fidelity, and fruitfulness.  Without these, there is no authentic marriage.

Any custom or law that does not respect these four "marks" of marriage is unjust.  Though we take them for granted and have come to consider them normal, laws allowing for divorce and remarriage are intrinsically unjust.  They violate the dignity of marriage, its nature of indissolubility, and are a blemish and a scourge on the society which lives under them. 

A fortiori, laws that allow for polygamy or same-sex ...