I'm with Lighter -
I can't figure out how in the world it could be, that a homosexual marriage is a thread to my heterosexual marriage. All I can figure is that these people figure that if homosexuals can't marry homosexuals, they'll marry heterosexuals instead and somehow get "cured." I've known one homosexual who tried that, and his wife thought he was the perfect husband until she discovered he had hundreds of male lovers. The results were disastrous, and came close to destroying the two children of that marriage.
My religious faith tells me that homosexuals should not marry heterosexuals. I don't have any reason to think that religious authorities who oppose gay marriage, have any sort of legitimate enlightenment in this matter.

-Joe-