Marriage is man+woman --> possibility of progeny to support parents and the civilized state . . .So, when my uncle married his second wife at the age of 80, it was an invalid marriage? I still don't understand why this is an issue: first of all, it happened in a foreign country, secondly no one forces any religion to accept the marriages of any other religion or purely state marriages, and third, I always thought personal autonomy was a tenent of conservatism, and the individual should be free to manage his money (and his estate) as he wished.
tenet
"married his second wife at the age of 80, it was an invalid marriage?"
No, why would you think so?
The gay person can manage his estate and money as he wishes. He can even marry, provided the marriage would be consumated and not merely for convenience -- he just can't "marry" another man.
Personal autonomy is a tenent of conservatism, but not personal license. Conservatives follow the tenents of Nature and Nature's God. I.E. reality: the NATURAL law, as discinct from any specific religion. In fact, the natural law is incorporated into the teachings of religions, to a greater or lesser extent. Some religious sects could "marry" gay people in a ceremony, but that would not make it a true marriage. A mere religion cannot supercede the natural law, nor can the state.
As for not being forced to recognize the marriages of the state or other religions: try being an employer and refusing to withhold at the married rate . . . etc.
It is the utopian who tries to recreate the world in his image or to fit his philosophy, not the conservative. "Gay marriage" is an utopian notion, not a conservative one. Implementing utopian ideas by force of the state does cause harm. Agreeing with the natural law is not utopianism: it is merely recognition of the way things are.