As someone who does not believe the government should sanction gay unions, I will readily admit that religious belief is the underpinning.
However, I believe that God's laws were designed not to deprive us of pleasure, but to protect us from dangers, seen and unseen. Thus it to our mutual benefit for all of us to obey his teachings, even those who do not believe.
Of course, this must be balanced against the notion of freedom. Indeed, Jesus says that he will convict the world of sin because they do not believe in Me; so apparently, his priority is faith first, then behavior. And Paul informs us that we should indeed judge fellow believers more strictly on moral issues than non-believers. So there is a case to be made that the Bible does assume a certain civil freedom that we Christians should not necessary indulge in.
Nevertheless, I find it reasonable that our beliefs at least contribute to our opinions about what should be codified in law.
You've been making some interesting points, but your last comments seem to be a call for a theocracy.
You can't ask folks in a free contry which does not have a state church to follow your religion because you think it's a good idea.
I figured some of your Scripture hounds might catch my error :)
I don't see how you expect the injunctions of your religion to have any force at all for non-believers.
Of course, religious and secular ethics may agree at certain points-murder should be prohibited, etc,-but they may vary widely at other points.
Since even Christians can't agree on many points of ethics, how can your interpretation of ethics be convincing for people who aren't even Christian?
I think the solution is to have civil unions for hetero and homosexuals, and leave marriage as a religious concept to be dealt with privately with a religious organization of your choice.