Must moral law be divinely inspired?

[JPolin]

I'm an agnostic, largely because I have not taken the time to study religion or read religious texts. I found it premature to make a determination one way or the other without an informed opinion. Now I attend a fairly conservative graduate school, and one of my classes concerns the Western moral tradition. For the first time I'm devoting significant attention to issues of moral philosophy from Greek philosophy all the way up to Deconstructionism/Post-modernism.

The central contention of the Western (Judeo-Christian) tradition is that law (in a moral sense, i.e. "natural law") derives its authority from a higher power. Thus the 10 Commandments serve as the objective basis for right and wrong in Western civilization. A transcendental divine presence (God), in this conception, issues the 10 Commandments and serves as the bedrock upon which this moral foundation lies. In the Judeo-Christian tradition, natural law offers a guidance towards the good (in an Aristotilian sense i.e. Nicomachean Ethics), which will aid people towards a path of salvation.

If one does not believe in this objective natural law, however, one must look for an alternate source of moral clarity. For thinkers of the Enlightenment, Reason became the center of the moral universe. Many Enlightenment thinkers believed in Deism, where a transcendental presence created the universe but does not have any influence on material events thereafter. With Reason as God, moral philosophy became a subjective matter, something determined in the minds of men.

Here lies a significant problem, though. If the moral basis for law is to be determined by men, which men shall determine it? In this subjective world, how does one decide which men how others shall live. The eventual outcome of the concept of divine Reason is the eventual moral relativism and Deconstructionist thought of modern times.

Subjective morality and blind faith in flawed reason have led to the worst excesses of human history. Both Nazism and Soviet Communism speak to failures of human-based moral systems. Moral relativism and deconstructionism have both eroded the foundations of morality without providing an alternative source of authority.

Thus I now understand the necessity of having an objective right and wrong. And this is not a uniquely Western concept. While the Judeo-Christian tradition calls its values the 10 Commandments, all major world religions believe that it is wrong to kill, steal, etc., and right to honor family. Since many of these basic precepts are common to all religions, it seems reasonable to me that they assume a certain transcendental value of truth.

But the next leap is one I'm not able to make. If there is a transcendental set of truths, there must be a divine presence responsible for these truths. In order for this natural law to have any real meaning, one must have faith. And as rationalistic as I am, I can't really come to terms with this concept of faith.

So there's the conundrum. Am I right to assume that moral/natural law necessitates a divine presense? If so, how does one make the connection to understanding the nature of that presense? If not, where does one obtain the authority to craft laws, as well as right and wrong?