Margaret Cho write an eloquent argument for gay marriage that I wish I wrote instead of this one.
Update: Actually, I just thought of more to say: The only snag is that, although America is set up as the land of the free and the home of the brave, the religious right has constantly put forth the argument that America was set up as a Christian nation, and that it is evil people like Madlyn Murray-O'Hair (sorry if the spelling is wrong) and the ACLU, among other elements, that is ruining the country and will bring about God's wrath. They also point to examples in the Bible such as the Jews wandering the desert for 40 years after the Exodus and the dissolution of Israel, and saw that God will do the same thing to us if we don't obey and follow His Word. The wife is totally into that camp, and I even heard a radio show after the Super Bowl Brouhaha (I think it was this one, but I can't say for sure) that said the Al-Queda and other terrorists were pointing to this as examples of how evil America is, and will use it as a recruitment tool and inciting them to more terrorists acts. Scare tactics is a big part of Christianity, starting with a God that will send to Hell and eternity of tortures and pain if you don't believe in Him as you should, up to if you're not a believer when Jesus comes back, you'll go through Hell on Earth that is called the Tribulation.
Since the religious right has the Republicans in their pocket, that's why this has become the controversy that it is. As Ms. Cho says, it's time to put up, and do what we say we do, or just trash it.