[marktwain]

“But if love and mutual consent become the definition of what the boundaries of marriage are, can we as a society any longer even define marriage coherently?”

Precisely. That is the end game. “Gay” marriage destroys the definition of marriage. It becomes a meaningless term, simply a way for people to step through bureaucratic hoops to get certain privileges from the state, having nothing to do with the structure or stability of society.

[Gluteus Maximus]

But you see, the "redefinition" of marriage precedes "gay marriage" by decades. The first "redefining" moment happened when the Anglican Church permitted artificial birth control for married couples. All else flowed from that. Once "marriage" is redefined to include intentionally sterile sex, then anything goes. Gay marriage, polygamy, and soon bestiality and pedophilia all follow directly from that first fateful decision.

The harsh truth is that gay people didn't destroy marriage, contraception among Christians did.