The lovely and talented Ellen DeGeneres has been quoted as saying, "I believe that someday we'll look back on this and not allowing gays to marry will seem as absurd as not allowing women to vote."
Of course, to most people same-sex marriage should seem like a no-brainer, akin to racial equality and women's suffrage, as Ellen's quote suggests. However, while it seems to make sense on the surface, there is one essential element that unfortunately renders it impossible: religion.
As far as I know, there is nothing in the bible that specifically prohibits women from having the vote (although religion certainly does its part to prevent women from enjoying the same status as their male counterparts - but I digress). People who were opposed to the female vote didn't necessarily have direct biblical passages to quote, and no one can really prove that female suffrage goes against the will of god. But homosexuality is another story.
One of the scarier sections of the bible, Leviticus, does make mention not of same-sex marriage, but of homosexual acts.
Leviticus 20:13 states: "If a man lies with a male, as with a woman, both of them have committed an abomination: they shall surely be put to death; their blood shall be upon them."
All those who oppose gay marriage can invoke these words and claim to have god on their side. An even bigger problem is how much political sway is given to these religious bigots. Same-sex marriage is legal now in Canada, but I don't see how America will ever get there at the rate they're going. Politicians in the US who even want to be considered for candidacy have to make loud, public proclamations of their (Christian) faith and end every speech with "god bless America". Evangelical nutjobs have massive voting power, and they know it. They are constantly being catered to, either because the politicians are religious themselves (a la George Bush), or because the politicians know whose ass they have to kiss if they ever want to see Washington.
So, with all due respect to Ellen DeGeneres, it is wishful thinking to hope that same-sex marriage will one day go the route of the woman's vote. So long as the words of the bible have influence on the public political sphere, there are people who will feel justified in their hateful, prejudiced, discriminatory ignorance. Yet another way that the beliefs of one group can infringe on the rights of everybody else.