Ake, you keep ignoring the main point we are trying to make: that "living together" is not the issue, but being privy to the legal benefits that marriage accords is.
And while the "homosexual lobby" might not be totally satisfied with civil unions that provide the EXACT SAME legal benefits as "marriage", it's a damned good start.
No one that I know is arguing that churches should be forced to change their sacraments. If they want to be exclusive and look down from on high at those they disapprove of, as you point out, that is their right. But it is NOT their right to deny anyone their legal rights because of something they choose selectively to enforce (again, we hardly legally enforce every single prohibition in Leviticus, or else we'd all be living very differently).
And as for your claim that "ONE man and ONE woman" has been the sacred definition of marriage for thousands of years, good Lord, man! Apparently the words "harem" and "concubine" are hitherto undreamed of in your philosophy. Sheesh. Have some historical perspective, for Frith's sake.
No, my dear, I would never claim that you want homosexuals to be exterminated. But I don't see you advocating a solution that would allow them to live with the same dignity, respect and equality under the law that they deserve, either. And no amount of kvetching on anyone's part will convince me that any faction large or small, be they Christian, Muslim or Scientologist, has the right to deny full legal marital privileges to gay people because that would "water down their sacred institution". It's being watered down just fine as it is, ta very much.
P.S. At some point, I would be very interested to hear your personal opinion on this matter. Feel free to PM me if you don't want to lay it open to public consumption.