The government intervenes and regulates those aspects of human life that have a some bearing on the common good, and which may be made subject to state power (the amount of rainfall profoundly affects the common good, but it isn’t subject to state power). Interstate commerce, for example, is a critical part of our national life, and it must be regulated in order to be sure that it serves, or at least is not contrary to the common good. Other examples are the buying and selling of real estate, the licensing of drivers, the establishment of traffic laws, and so on. All of these activities share the characteristic of being activities that individuals undertake which have profound effects on the lives of others. In order to make sure that this profound effect is good, the state crafts laws that encourage citizens to undertake them in ways that serve the common good. There are many other types of human activities that the state leaves unregulated precisely because they have no effect on the common good. There are no laws, for example, regulating the celebration of birthday parties or the playing of tic-tac-toe. The state leaves the undertaking of these activities entirely to the discretion of individuals.
The state enacts laws to encourage and regulate marriage precisely because it has been thought for some time now that the common good is profoundly served by a man and a woman getting together and remaining together for life. The most obvious societal good is the propagation of society by the production of new citizens who do things like serve in the military, pay taxes, and become productive members of the work force. If there were no benefit to the common good, marriage would be like foosball or birthday cakes: the state simply wouldn’t care to become involved and marriage would a purely private concern. There would be no tax breaks so mothers could stay home with their children to make sure they become educated and keep out of trouble. Financial benefits such as the extension of health insurance to include family members are given to married couples for the same reason, in order to facilitate the growth and expansion of families, something of great benefit to society.
Thinking then of homosexual marriage, one must ask: "What compelling reason does the state have in granting them the rights of heterosexual couples; what goods are achieved when homosexual persons contract to live together, and how would the common good be served in granting them the same benefits of heterosexual couples?" One would be hard pressed to make a case that there is any good served by encouraging homosexual persons to marry. In light of the lifestyles of the vast majority of "married" homosexuals, the benefits that would accrue to them with a "married" status – shared health benefits, tax breaks such as married people might enjoy – would result only in their own enrichment. Those governmental bodies approving gay marriage would be merely making provision for the subsidization of a more leisurely life for homosexuals. This argument, of course, makes no moral claims. It isn’t arguing, for example that homosexual activity is intrinsically evil, it’s simply pointing out that there is no compelling reason for the state to be involved in regulating the love lives of homosexuals, and so it should stay out.
In light of this we can see that the movement to establish the legal recognition of homosexual marriage does, as the voices crying in the wilderness claim, undermines the institution of marriage as that has been traditionally understood in the Christian West. The suggestion that society stands to gain as much from encouraging two men to live together permanently as it does from encouraging a man and woman to do the same is as degrading to the latter as it is ridiculous. Proponents claim to exalt the dignity of marriage, opening it to all, homo and heterosexual, when in fact the real effect of their advocacy is to convince society that marriage is nothing more than a self serving enterprise made desirable by the benefits that accrue from the (fading) social esteem given to married persons, and the legal and financial benefits associated with that state of life. The great offense of legalized homosexual marriage is to empty the notion of marriage of all its meaning, to reduce it to a means of personal gain and self-satisfaction. This is hardly surprising, I suppose, in light of what marriage has become for so many. In our own time married couples have severely limited the size of their families by contraception and abortion, making their heterosexual marriages nearly as self serving and lifeless as homosexual "marriages" would be. One might imagine the homosexual person looking on such the average married couple of today and thinking, "I’m at least as capable of having such a sterile and lifeless relationship as they have, so why shouldn’t I also get to enjoy my lover’s health benefits?"