I think you need to tell us what your definition of "abomination" is, and why you feel same sex marriage fits that definition.
If your definition of "abomination" parallels that of the online dictionary as "a thing that causes disgust or loathing", please tell us why you find same sex relationships disgusting. Or why you loathe same sex relationships.
Disgust and loathing is not about the production of offspring - it is much more personal and visceral than that. I suspect in your case it stems from your imaginings of what same sex couples do in their private sexual relationship, and you find that unpalatable.
So tell me - what has it got to do with you, what two consenting adults do in private? Mind your own business. Stop obsessing about other people's sex lives.