I've always had difficulty with the gay marriage issue, and even now it seems I'm having trouble giving a straight answer-- and this has nothing to do with religion (or at least any established religion).
I'd also mention I'm not homophobic-- I have no issue with seeing the gay men have relations in public, and some of my best friends are gay, lesbian, or bisexual. I've also dated a bisexual girl, and been kissed/hit-on by gay men without feeling anything at all (except for a lack of attraction, so the same reaction I'd have to a plain/uninteresting female).
My issues have more to do with my view of marriage itself, and not homosexuality.
To me as well, marriage isn't between a man and a woman... It's between the couple on one side and the community/society on the other.
It's the agreement of the couple to build a family-- the building block of society; to raise children and, as a building block of society, to perpetuate/continue that society and its culture. It's the promise of the couple to join the society as "full adults" (where the idea of marriage as a coming-of-age ceremony) by agreeing to obey society by building a family that is at the root of it.
In a general sense, it doesn't make sense for homosexuals to marry, because a homosexual relationship unarguably does not do any of the things above. That is, it clearly breaks tradition (at least in the US), breaks society instead of joins it (look at all the conflict surrounding it), and finally... can't produce children.
That being said, hetereosexual couples in this day and age are little better, because people view marriage as a part of romance, rather than as the family building. Well that's not strictly true, as everyone clearly sees the connection between marriage and family in culture. That said, too many people are more concerned with finding true love and being passionate with their partner rather than the true objective-- building a good place for your children to grow up. The 50% divorce rate is flat out embarrassing, because you know that it's not all about broken homes with terrible parents or civil abuse-- you know that a lot of that 50% just comes down to selfish parents. Any of my arguments based on the sanctity of a traditional household and family building get shat on by the selfish actions of unworthy heterosexual couples. Of course that's also unfair for me to say, and still a good portion (if not a majority) of people grow up in good families with parents who are dedicated to each other, and more importantly to their children (as was my household).
I'll say it again, and again, and again: Whether you're gay or straight, marriage isn't something you do out of selfishness or your own sense of entitlement. Marriage is only meaningful with dedication to the family, and the blessings of the community.
At the root of the issue though, is the fact that society doesn't need more children born. The world faces over population, and societies struggle not with gaining the members to maintain itself and survive against the wilderness, but rather with how to feed all its peoples and find them places in the web. In other words, there's really no need by society for all families to make children. In fact, couples who will raise unwanted children without producing their own-- society could only benefit (unless you happen to be Japan, South Korea, or Italy apparently, who have extremely problematic birthrates... then you get to do whatever legislation you want in order to force people to have sex and kids, lol).
When culture no longer fits the mold, no longer makes practical sense, culture should change. Forcing people to change their culture is a monstrous crime, but if culture makes no sense, it should change-- and will, given time. If it no longer makes sense for families families to be strictly founded on a male/female couple, culture will change to accommodate.
Still, because of my strong feelings about family and marriage, I can't really give my blessings to gay marriage... it just feels wrong.
I would rather have marriage stop being a legal institution altogether, with heterosexual couples also having "civil unions," and that marriage as a concept be preserved only in tradition and ceremony. As ceremony alone, perhaps its traditions and intentions could be preserved by those who value them.
If the above post does not make it clear, the notion of churches being "forced" to marry people is outrageous, infuriating to me. NOT because of religious freedom/importance/whatever, but because a marriage without the good wishes and intentions of all those present, will only make for a sad household. Marriage isn't something you do out of your own selfishness or "right" to do it-- that is exactly the attitude that makes for so many bad heterosexual marriages. Marriage isn't only for yourself, it's also for the family and community. Marriage without the acknowledgment of the community is simply not marriage.
Whether you are gay, or straight, it matters not-- marriage is not between two people, it is between the couple on one side, and the community on the other.
Marriage has meaning only because of love, acceptance, and the good wishes of the community for a couple, and belief in the couple. Whether you are gay or straight, marriage is the formation of family, and joining the community. A marriage that parties are forced to not only accept, but acknowledge... that cannot possibly make anyone happy...
By the way, I have actually seen what I believe to have been an alien space craft, so I voted "YES" for the poll. Aliens exist my friends.