Actually, banning gay marriage is not unconstitutional. Gay people have the same right to marry someone of the opposite sex as straight people.
This cartoon was made just for you!
Anyway, our problem in the US isn't with gay
marriage, it's with marriage in general. To the government, marriage is a very broad power-of-attorney between two people that grants a specific set of privileges and responsibilities. To the religious, marriage is a holy union between two people, blessed by God, Allah, Vishnu, or whoever. Many religious folk have conflated these two ideas to the point that they can't see the difference anymore. The problem (for them) is that, at the end of the day, the marriage is only valid if the proper forms are filed with the government. I can, for example, walk down to the courthouse, sign some papers in front of the county clerk, and become legally married with no religious ceremony whatsoever involved. On the other hand, if two people have a ceremony at their church and get their union blessed by every holy man they can think of, they're not "married" in the eyes of the government unless the proper paperwork is filed.
Because marriage grants certain rights from the government such as tax filing status and inheritance, the government has a vested interest in regulating marriage. Some churches say that only a man and a woman can ever marry. Others, like the Episcopal, Unitarian, and MCC say that it can be between same or opposite sex couples. Unless there is a good secular
reason for doing so, the government is prohibited from taking one interpretation over the other by the First Amendment. The only fair way for the government to proceed is to allow any two (or 3, 4, etc) consenting adults who desire to do so to enter into the legally binding contract that we call marriage.
As for gay marriage being a state issue, sorry but no. That's absolutely wrong. Marriage crosses state lines. The commerce clause gives the federal government supremacy in these cases, and there's a very good reason for it. Let's say that a homosexual couple is married in Massachusetts. They go on vacation to Germany, one is struck by an automobile, and is lying brain-dead in a hospital. The spouse, seeing that his husband is already dead, asks the hospital to remove him from life support and let him die peacefully. The German government is going to contact the US State Department and ask them to confirm that these two are, in fact, married before they comply. This is not
a state issue at this point. The US government has a compelling interest to have a single standard that says either yes, they are married or, no, they're not married.
Here's another example: Let's say that two men get married in Iowa(!) They take out a joint credit card and run up a balance of $20,000. With marriage in general, the laws are pretty clear on how this works - both parties are equally responsible for the debt, even if only one of them was doing the buying or even knew about the purchases. Here's the wrinkle, though. Let's say that they move to Kentucky. Kentucky, and most red states, don't recognize gay marriages, even if they were performed in a state where it was legal. So now, we have a problem. The financial laws are pretty clear with regard to married
couples, but Kentucky says they're not married. By that standard, they shouldn't have even been able to open a joint credit card account in the first place. Are they off the hook for the debt? Again, this is a case where there is a compelling case for the federal government to have one single definition of marriage. Letting the states decide means that the rights and responsibilities of these people actually change as they change addresses unless there is a single federal definition.