Divorce, Prohibition … Gay Marriage?

Regarding my article, Gay … But Not Funny, a recent commenter stated:

Churches have every right to state their views on sexual morality. Nevertheless, the question is whether in a pluralistic democracy, should we legislate how people conduct their private interpersonal relationships by criminalizing gay conduct? If so, we must then also make non-biblical divorce and remarriage illegal and prosecute extra-marital sexual behavior.

Legalizing gay marriage is a little different, of course, but the question must be taken outside the conduct of what the religious ideal of marriage is.

Some view any consumption of alcohol a sin. Should this belief dictate that we return to Prohibition or vote on banning its sale?