"Moral imagination..." I like that. Jeffrey Dahmer had a moral imagination. It's really funny that you say morality cannot be prescribed when, by the very definition of it, morality is prescriptive. It is telling you how you should live. It wouldn't be very helpful if it was telling you how you or someone else (i.e. "society") lived. Morality cannot be dependent on one's own arbitrary definition or else it loses all meaning. Murderers and rapists could come up with reasons why, in their moral imagination, murder and rape were completely acceptable, and who would you be to tell them that they are wrong and you are right, just because you think your morality is superior? After all, this talk of a "moral imagination" kind of contradicts that.
The point of my post was that it doesn't matter what you think of my moral effectiveness in the world because my morality tells me how to live in accordance with others, and it just so happens that I found that morality in the Bible. Where did you find yours and why should everyone accept it? If nobody has to accept it, then how can we punish people for doing things that are immoral? Do we completely rid the world of any laws?
Also, one point: the Constitution has already borrowed heavily from Biblical law. The court system? Jury of your peers? That was in the Bible. If you don't have an objective morality (you decided to tack the word "dogmatic" on there), then how can you expect anyone to adhere to your moral principles? According to you, I should be able to, as my own free agent, imagine a morality in which I can shoot you and it would be totally fine.