I'm different because my opposition to polygamy isn't based on an irrational religious hatred of the individuals involved.<quoted text>
Why do you find a marriage of three adult atheist men objectionable?
The bigots against SSM consider your marriage objectionable. Why are you any different from them?
I object to 3 adults (regardless of gender or religious belief) from marrying because such a marriage would open the door to an equal protection argument for traditional polygamists who won't limit their marriages to adults.
In addition, polygamous marriage is incompatible with all existing state family law. The entire family law code would have to be rewritten in every state to account for multiple spouses in regards to parental rights, property ownership, inheritance, etc, etc, etc.