The answer to whether or not gay couple's can marry is very simple:
Society gives us to types of marriages, spiritual, which is what happens when you get married in a church, or elsewhere by a priest or some other religious figure.
Then there is being legally bound to each other for taxation, legal purposes, medical purposes, basic *rights* which are given to all men/women under the Constitution of the United States. It says it in the start of the constitutional itself, 'all men are created equal', men in this context, being mankind.
To deny anyone any right, is unconstitutional. It's not a matter of being for or against gay marriage, or being for or against homosexuality, it's basic constitutional rights. Everyone needs to pull their heads out of their asses and read the constitution before people run it over to where there's nothing left of it.. it's so close to happening and the ignorance of the average American person towards it isn't helping.
This isn't a religious issue or a sexuality issue, it's a constitutional matter, the issue is black and white, plain and simple. They're legally being denied rights they have in every state, by laws in the state stating 'marriage is between a man and a woman' that in itself is unconstitutional, I would love to see any religious person tell me it's not, the only way it could be is, if homosexuals were subhuman, which they aren't.. homosexuality roots back just as far as humanity itself. It pre-dates Christianity.