Lawrence Solum has an interesting post that examines Justice Thomas’s belief in the natural law of the Declaration, complete with its reference to a “Creator," and notes how we might square that belief with the Rawlsian notion of secular “public reason" that ought to underlie judicial decision making.
Solum references an article by Thomas Krannawitter defending not only Thomas’s belief in the natural law of the Declaration, but stressing in his defense
the principle that our rights come not from government but from a "Creator" and "the laws of nature and of nature's God," as our Declaration of Independence says, and that the purpose and power of government should therefore be limited to protecting our natural, God-given rights.
To which Kevin Drum replies
Coming from a priest or a preacher, this would be fine. Coming from a Supreme Court justice who's supposed to interpret the constitution on secular grounds, it's an embarrassment.
Solum notes how it is possible to adhere to Rawls’s ideal of public reason, with its demand of secular rationale for public policy and still believe that rights ultimately derive from a Creator. I concur. And I think it’s very important that secularists not reject the Declaration because it invokes a “Creator.” The Declaration’s invocation of a “Creator” ought not to be understood as transforming it into any kind of “religious” document, more appropriate for “priests or preachers” than for public officials.
First, the Declaration is a document of “man’s reason”; it’s not any kind of essentially religious document, not even an essentially Judeo-Christian document—because it's not clear that the God of the Declaration is the God of the Old Testament—something that might unite Jews & Christian. It is not clear that “nature’s God” gives any commands, nor that he is a jealous God, which are characteristic features of the Judeo-Christian God. Moreover it’s not clear from the Bible or traditional orthodox understanding of Christianity that God grants rights, unalienable or otherwise. And it's certainly not clear that nature’s God was the Trinitarian God of the New Testament (given that the majority of the drafters of the Declaration rejected the doctrine of the Trinity and how widespread deism and unitarianism were among even many of the founders who were members of Christian Churches).
So who is nature's God? As Claremont's own Thomas West has noted in a speech he gave to the Family Research Council on John Locke, "nature's God" "mean[t] God insofar as we can discern his existence through our reason unassisted by faith." If "secular" = universal Truth accessible to man as man, from unaided reason, then the concept of "nature's God" is as close to a secular concept of God as one can get.
Nature’s God was in many ways a lowest common denominator version of God. Any monotheist, whether a Protestant, Catholic, Muslim, Jew, Deist, Unitarian, Trinitarian or non-Trinitarian, could believe that nature’s God was their God.
I know that, of course, atheists and polytheists are not united under this concept. But, nature's God according to Jefferson gives men an unalienable right to worship no God or twenty Gods, thus including atheists and polytheist within the rubric of the rights of conscience. In fact, the rationale behind many of the present Establishment Clause battles, (for instance, removing the “under God” from the pledge) simply takes the founders’ logic of religious rights and seeks to lower the lowest common denominator to include atheists & polytheists. But that in turn, would require removing all references to a “Creator” from the public square. I’m not sure we should go that far. References to a singular “Creator” should be permitted under the Doctrine of Ceremonial Deism if for no other reason that so many of our important “rights of man” natural law documents ultimately tie rights to a “Creator.”
Another reason why our founders tied our liberal order to God: They had to. We could not have made the theoretical case for revolution without invoking God. Remember what our founders and John Locke were arguing against was the divine right of Kings, most famously articulated by Sir Robert Filmer. Divine rule of Kings ultimately tied the right to rule to God, therefore liberal democracy similarly had invoke God, or else Divine Rule of Kings would have “trumped” it.
Let me note a few things. First, Filmer defended divine rule of Kings on explicitly Christian grounds. Locke also invoked Christianity in his defense of liberal democracy; but I’ve heard it argued (by the Straussians) that Filmer’s case was in fact more consistent with the then understanding of orthodox Christianity than was Locke’s. I’m sure Jeremy Waldron would disagree. Certain versions of orthodox Christianity may indeed be compatible with liberal democracy, but other versions of orthodox Christianity are every bit as compatible with illiberal forms of government like divine right of Kings.
The Straussians also argue that Hobbes & Locke’s, and hence our Founders’ premises were atheistic at heart. They may have invoked a “nature’s God,” but these atheists did so only because they needed God as the ultimate “trump.” But in any event, the Straussians argue, even if Locke and our Founders did believe in God (as they said they did), their concept of a rights granting nature’s God and Locke’s state of nature theory itself is so “wholly alien to the Bible” (as Strauss himself put it) that it amounts to a denial of the Christian God. This is what Allan Bloom meant when he wrote in The Closing of the American Mind, “[t]he philosophers appeared to deny the very existence of God, or at least of the Christian God.”