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.
Good question, WackyKat. I am not suggesting that I should impose my religious views on others; I should convince people of them. Obviously, I can't just throw out "because God says so" when trying to convince an atheist as to why a particular behavior is harmful.
And indeed, God seems to prohibit things that society frankly has no problem with. But my faith tells me that God's laws are not to deprive but to protect. From that underpinning I can search for logical and verifiable reasons why that is so, and attempt to convince others of them.
Obviously, I would prefer to convince someone of faith in Christ; but barring that, convincing him/her to abstain from behaviors that are harmful is worthwhile. And if enough people become convinced of a particular "sin" (even if they choose not to label it in that way), then it becomes appropriate to consider codifying it as law.
It may sound like I'm walking a fine line between theocracy and freedom here. But the thing is, everyone gets their morality from somewhere. I would argue that man gets morality from God and then chooses to corrupt it. Others may feel morality can be completely reasoned out, free of theistic influence. But whatever basis they have, they must enter the arena of ideas, join with others who share their beliefs, convince others who do not, in order to form a society of laws.