I would suggest that it is simply not addressed. Reading through the Scriptures, it appears to me that the same sex sexual relationships that are condemned are those that are of an idolatrous nature (sex with prostitutes as a form of worship of false gods).

Comparing that to a loving, monogamous relationship between two people of the same sex simply makes no sense.

Regardless, even if one finds that it is sinful, I cannot understand how that plays into extending the legal rights to committed same sex partners that are extended to non-Christian heterosexual couples. We recognize that marriage benefits should be an option to people regardless of their faith. So while you SAY that all sins are the same, this one is clearly worse because you suggest that there should be legal ramifications accompanying this one that do not apply to other sinful couples.