The differences between race and sexuality are not interchangeable. So many people play that card, but I feel that is a weak comparison that is just meant to make people feel guilty.
Not allowing a black man to marry a white woman is not the same as not allowing a man to marry another man. It's just not the same at all.
It's really not.
You're sugesting that the government should pass a law that applies to one group of people because of factors they are BORN to.
Like, you even use it as your argument. The marriage of a male and female is special because it's a natural union that could, in theory, produce offspring. This is a fact of birth and not a decision being made.
Just like being born gay is a fact of birth (or a result of some event in early childhood) and not a decision being made by the person.
Just like being born white is a fact of birth.
Can you actually argue that it is GOOD for a law to be based on something that is nothing more than a fact of birth?
Should we have different laws for people born to different circumstances?
You can argue that it's a "natural" pairing all you want, but that argument can also be used to say that marriage between two white people is a "natural" pairing because that's how we developed in nature.
Tell me, if it were discovered that some aboriginal tribe in Australia had evolved such that they were biologically unable to breed with a man or woman from the US, would you make that "marriage" illegal?
It's a slipper slope. There are no circumstances under which you can justifiably deny someone a right JUST because he or she is born with specific genetic traits. Either he or she is human, and therefore deserves all rights that humans are given, or else he or she is not. There can be no subclassifications where some are given specific rights that others are not.