It threatens the traditional family unit by giving governmental sanction instead of shame. It’s EXACTLY analogous to the “sexual revolution’s” contribution to the lost stigma and shame of out of wedlock pregnancy and its affect on society. Homosexual marriage will change the culture’s perception of what is the ideal family unit and the mores that come from that tradition by increasing the frequency of this chosen behavior. The more people taught to be homosexual the more chaos it brings to society.
This is all a distraction away from really important issues, IMHO.
What’s more important than family?
You're kidding, right? Do you really believe you can teach someone to become homosexual? I'll bet you one trillion dollars you, or anyone else, cannot teach me, or any other heterosexual, to become homosexual.
While homsexuality may be immoral and a biological disaster it is not contagious.