First and foremost, there is nothing unconstitutional about gay marriage. Gays have equal rights that all other people in the U.S. do. By getting married, they are in no way interfering with anyone else's rights. If we intend to have equality in this country, why are we keeping a certain group of people from marrying? Now you can't get into the legal aspect without mentioning separation of church and state. Since marriage is a religious ceremony, the state can't touch that part of it. However, when two people get married, a name gets changed and with it, an entire series of legal and completely secular things happen. The person usually has to change the beneficiaries on their financial accounts (401k's, IRA's, etc…) and if anything like a house is bought it's considered both of the spouses' property.
Some people will argue that they shouldn't marry because it's not natural. First, let's define "natural". Natural means (in this context) present in or produced by nature. Well if we are going to ban gay marriage because it wouldn't be natural, then we ought to ban all marriage. After all, marriage isn't present in or produced by nature. If anything, the reverse is true; homosexuality is found in nature and marriage isn't. Another phrase people like to use is "it's not normal". What is normal? The definition of "normal" is adhering to a common standard, pattern, level or type. All normal really is, is what somebody is used to and sees most often. In Newark, it's normal for a kid to bring a gun to school; but in a peaceful suburb, it isn't.
Gay marriage doesn't harm anybody. The only people that are seriously affected are the ones getting married. It won't keep America from winning the war, create anarchy or make the economy collapse. Speaking of the economy, it would probably help it. Think of all the money people put into ceremonies and receptions. They pay for catering, gowns, tuxedoes, the space to have the ceremonies and receptions, the invitations. The list goes on and on. If anything, gay marriage would probably help the economy.
And for all you homophobes out there, consider this. Sigmund Freud developed the theory of a psychological defense mechanism called projection. In projection, the person has a bad quality and instead of dealing with it, they throw it on to others or attack people with that bad quality. By doing this, it now becomes the other person's problem, not their own. To sum it up, homophobes are simply attacking the gay population because gayness is something they hate about themselves and to make themselves feel straight they hate gays. Besides, studies show that homophobes are usually in the closet gays.