One problem in the discussions of homosexual marriage has been semantic: if homosexuals ought to be permitted to “marry”, what is wanted? “Marriage” means different things to different people, and different things to the same people in different contexts. Filing under the income tax status “married” is an entirely different issue from having a church wedding.
For centuries, “married” meant lawfully permitted to live together and engage in a sexual relationship; marriages were generally registered with a local church or courthouse so there would be records–you did not need a license to marry, but once married you could not easily divorce. Such legally enforceable permanent relationships no longer exist in the western world; it obviously is not what is sought. The part that remains–the right to cohabit and engage in sexual relations–is already available to any adult.
“Married” also means married under the laws of the state–in our time, obtaining a license and being registered. This developed as a means of regulating sexual activity–preventing polygamy, incest, and adultery, later preventing miscegenation, then controlling sexually transmitted diseases. Only the last remains a viable legal basis for the state to regulate such relationships, and it is doubtful that homosexuals want mandatory blood tests before engaging in sexual relationships. The concept of licensing, though, inherently means that a license can be refused on some basis–it is a regulatory scheme that says the state can forbid the relationship.
There are also the legal benefits of being “married”–the incentive aspects. As covered, these are either unconstitutional or legitimized by something other than a personal relationship with a sexual component–establishing responsibility for offspring, identifying legitimate heirs, or promoting population growth. If these are the valid bases for regulating sexual relationships between heterosexuals, then marriage regulations can only cover them; if they are not, then the government cannot regulate sexual relationships at all, and marriage licenses and registrations must be discontinued.
It might be thought that “legally married” would mean that such marriages would have to be regarded as valid by all religious groups. This is false as a matter of law–religious groups are not government organizations, and are independent of government control in such matters. It is also unrealistic. The Hasidim will never allow it; the majority of Islamic groups will oppose it. Although Christian groups (particularly Catholics and Evangelicals) are criticized for opposition, religious groups around the world and across the centuries (not all, but most) reject the idea of homosexuality as a “normal” state.
So what does the homosexual community want? Do they want to insist that it is inappropriate for the government to pursue social policies which protect children and encourage population growth simply because such policies give benefits to those whose relationships are likely to produce children in need of such protection? If that is the intention, the debate needs to be about whether heterosexuals should be permitted to marry and receive such benefits. We give financial assistance to the poor, and no one claims it is unfair that the rich do not get food stamps, because the program supports a policy of aiding the poor. If the entire point of marriage law is to protect naturally-produced children and promote their continued production, it is perfectly fair for such benefits to be extended exclusively to those in a position to produce them.
Or is the argument that people should not be permitted to have the opinion that homosexuality is aberrant sexuality? Even from a purely atheistic evolutionary perspective a homosexual sexual preference can be called dysfunctional, and any argument to the contrary is fundamentally values-based, and thus a religious/philosophical debate. Yet it may be that the objective is to turn traditional morality on this subject into “hate speech”, so that no one can express an opinion on the subject other than that which approves homosexual relationships. That means it is fundamentally about censorship, attempting to control and limit free speech by claiming special rights for those whose practices are regarded aberrant.
No one has yet suggested a constitutionally valid basis for the existence of marriage law that applies to homosexuals. Instead, by the use of rhetorical smoke and mirrors, those favoring the change have insisted that it is about equality. That definition of equality would mean that the wealthy are as entitled to food stamps as the poor, that the fully able are entitled to any benefits offered to the handicapped, and that all Americans should pay the same amount in taxes regardless of income. Law is about making distinctions between different kinds of people and different kinds of conduct, and of promoting those kinds which benefit the state in definable ways. Promoting relationships which produce children does so. Interfering in other kinds of sexual relationships does not.