I think Mongoose probably gets it. While I agree with the points being made by KT and Kara, we have to be sensitive to the fact that labeling people as homophobes (even when true) is not likely to make them friendly to the cause.
At least someone gets it. I really don't give a damn what people think of me for expressing my views, but at least be aware that, by slinging that term around all over the place, all you're doing is galvanizing those who oppose your own viewpoints. Which, as Prop8 showed in the first place, is generally a frickin' stupid way to get what you want accomplished. Nothing illustrates that more clearly than KT's adorable post up there. (<3 you too, man.) It's that heavy-handed, unilateral condemnation of another person's entire mindset, whether or not the accuser has even so much as spoken with said person, that cheeses me off the most. And again I say, by demonizing one entire side of the debate as "redneck fundie homophobes," you're doing something that's not all that remarkably different from the actual examples of such saying, "God hates fags." Hauling out loaded terms like that accomplishes absolutely nothing for anyone.
And yes, iamzack, I'm aware of how cliche and patronizing that statement generally is, but there really isn't any other way of putting certain viewpoints into context. Unless you know some other way of differentiating someone trying to make a reasoned point from the aforementioned lynch-mob types, that is.
As for my real argument, what the hell, I'm already in it up to my neck. I am just going to stick with the biological angle, since Battuta's quote makes a good jumping-off point (or leaves me just enough rope to hang myself, depending on your viewpoint):
As for the biological argument, the idea that non-reproductive sexuality is a waste, or not supported by evolution, is clearly flawed - there are many species out there with bizarre and seemingly counterproductive sexual systems that actually benefit the species.
I do understand that there are a wide range of sexual reproductive practices at work in the animal kingdom; as I implied to karajorma, I'm not going to sit here and deny something like bonobo chimps using homosexual activity as a means of group bonding and asserting dominance. (As even you admitted, the example you provided for humans is completely fictional, its theoretical merits aside.) But looking at the process more fundamentally, the biological purpose of sexual reproduction in animals is for just that: reproduction, the passing on of one's genes to a new generation of organism. From an evolutionary standpoint, the reason that we are differentiated into male and female genders, and the reason we have this plumbing between our legs, is to facilitate that purpose. We feel attraction toward members of the opposite sex in order to facilitate the eventual act of intercourse (insert pick-up line joke here) in an attempt to create offspring. The reason that males, by default, are so hard-wired visually toward picking up on attractive members of the opposite sex is for that purpose, as is the perhaps more emotionally-founded response of females toward males. Without that evolutionary need for reproduction, whatever we did have between our legs wouldn't have much practical purpose, nor would the social practices that facilitate it. While more complex practices like those Battuta alluded to can be beneficial in some sort of group dynamic setting, at the individual, mano-a-mano level, it comes down to the guy and girl trying to get together.
Now I'm obviously not trying to say that vaginal sexual intercourse is the only possible means for using one's sexual organs, but it does stand as the fundamental reason we have them in the first place. As such, it's biologically natural for males to show sexual interest in females, and vice versa. And as such, I would argue, any proof of a hypothesis like Battuta's nonwithstanding, the tendency to show sexual interest in members of one's gender represents the equivalent of an evolutionary dead-end. In short, it's something akin to a congenital defect (going strictly by the genetic propensity idea). Up until a few decades ago, homosexuality was considered to be a psychiatric condition; I'm of the opinion that it would be better described as a genetic one. It's something that got tweaked at the DNA level to the point where the individual is not only disinterested in, but flat-out averse to, the normal reproductive function of their sexual organs. At least in my opinion, trying to state that a relationship founded on that "tweak" is completely akin to that between a male and female without it completely whitewashes all of the implications associated with that original defect.
In the end, for me, I view homosexuality as a biologically-induced condition, in the same vein as something like Asperger's syndrome. And in that light, I don't see it as being beneficial from a societal or species standpoint for homosexual unions to be legally enshrined at the same level as heterosexual marriage.
So now I've said my piece. I don't expect anyone to agree with any of this, nor am I really interested in going back-and-forth incessantly over it, since I probably should have kept my foot firmly in my mouth and never posted in here in the first place, but there it is anyway. One thing I will say in closing, whether anyone believes me or not, is that I've seen
true homophobia in action, and it disgusts me as much as any form of prejudice directed at an individual for reasons outside of their control.