Marriage is a contract, in the secular sense. I don't see a problem with gay marriage, especially since we already have easy divorce and what not. I mean...what damage can gay marriage possibly do? That said...
...I read this radical sociologist saying that she loves gay marriage, because it signals the demise of marriage as an institution. I don't know if thats wishful thinking on her part, or if its backed by data or what, but...more people live together, get divorced, etc. than in generations past. Family disintegration is increasingly common, and not just because of divorce, but also...I dunno...people work a lot, jobs are unstable, people move, community bonds have disintegrated, etc. Anyway, I'm hoping that gay marriage will maybe help at least some gay+lesbian people lead a more stable life, if they can't/won't/don't come to Christ. From what I read, stable gay (male) unions have fewer sexual partners per year than uncoupled gay men. That's a step towards a more stable life. I see it has harm reduction, lol.
Gays usually have more money than straight people, so the issue has been shoved down our throats. He who pays the piper calls the tune...
...so we Christians just have to roll with it. I think a good first step would be strengthening the marriages inside the church and paying attention to what contributes to divorce in the first place, and helping people heal and move on after a split (without affirming divorce as a viable option for most people).
Speaking as a former sodomite, its hard to get a lot of gays to Jesus. I mean, maybe the liberal Presbyterian Jesus, but traditional Jesus? good luck. With society going the way it is, people don't go to church as much, anyway, and when they do, they want Christ on their terms or not at all. There's a lot of competition in the "religious market place."
So, pray. For the intellectually inclined, maybe having the courage to write books about the virtues of Christian sexual morality, without being too preachy or singling homosexuals out (there's plenty of adulterers and fornicators in every church in America, right?) would be a good step in the right direction.
Honestly, the way American culture is changing, the economy is going, etc...I think its "The End of Empire," you know?