This question has nothing to do with the themes discussed on this website. But I am going to answer it anyway.
From a legal perspective, people who engage in homosexual practices have exactly the same right to get married as everyone else. But like the rest of us, they must marry a member of the opposite sex. None of us have an unlimited right to marry whoever we please. For example, a man cannot legally marry his sister. And a women cannot legally marry a twelve-year-old boy. We all recognize that society has the authority to place certain restrictions on who a person can and cannot marry. The hot issue today is whether or not society should broaden these restrictions and allow a person can marry another person of the same sex.
Nearly everyone, on every side of this issue, has failed to understand (or at least has failed to explain) the underlying reasons why marriage is an important matter of public policy. Those who oppose same-sex marriage intuitively recognize that there is something wrong with it, but because they fail to adequately articulate the societal purpose of marriage, they have yielded the high ground on the matter to those who advocate it. The proponents argue to our feelings and emotions: “Why won’t you just recognize me for who I am! I’m a human being, too! With feelings! And you’re hurting my feelings by not letting me have the same ‘rights’ that you have.”
In our society today, the western notion of romantic love has combined with the American impulse to live and let live to create an atmosphere where opposition to same-sex marriage is regarded as particularly rigid, unreasonable, and insensitive. But from a purely societal perspective (as opposed to a biblical one), the formal recognition and sanction of marriage is not based on society’s interest in helping to boost anyone’s self-esteem. Society has no interest in my particular self-realization journey or anyone else’s. Society, on the other hand, does have a compelling interest in formalizing an institution that keeps men and women together for the purpose of child rearing and for assuring the certainty of accountable paternity.
Society and its institutions extend special benefits to men and women who make a commitment to stay together, not because it approves of heterosexual couplings per se, but because it has an interest in stable environments in which the next generation will be reared. From a societal viewpoint, there is really no point to same-sex marriage. If two people of the same sex want to make a commitment to each other, that’s very touching and endearing, but it has no bearing on anything beyond themselves, and thus, there is no material interest in society sanctioning, propping up, or encouraging it. Indeed, to do so actually undermines the value of real marriage, in that it embraces (from a societal perspective) the notion that marriage is ultimately a romantic institution, rather than a hard-headed, pragmatic one that forms the underpinning of the larger society. No-fault divorce has already worked much damage in this regard; same-sex marriage will only compound the disaster we are currently in the midst of.
As far as the Bible goes, the following verses are as clear as words can be:
“If a man lies with a male as he lies with a woman, both of them have committed an abomination” (Leviticus 20:12).
“For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature. Likewise also the men, leaving the natural use of the woman, burned in their lust for one another, men with men committing what is shameful, and receiving in themselves the penalty of their error which was due” (Romans 1:26-27).
“Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God” (1 Corinthians 6:9-10).
I would like to point out that to engage in a sexual act with a person of the same sex is placed in the same category as engaging in a sexual act with someone to whom you are not married. In other words, sex outside of marriage is just as deadly a sin as homosexual sex. Both the homosexual and the adulterer need to come to a place of repentance.