I hope to have much more to say on this book in the future; I haven't gotten it yet but am well familiar with what it argues, having read many of Reilly's articles and other commentary about his book, for instance the symposium on Reilly's book at Catholic World Report. It's a great symposium that features analysis that is pro, con and in between.
Daniel J. Mahoney's article is my favorite and it's in the "in between" box. What I see as key from his article:
Still, the Founders bought into what the great southern Catholic novelist Walker Percy called a “mishmash anthropology.” No moral relativists, they nonetheless adopted the idiom of the “state of nature” which was intended by its great proponents to be a substitute account of human origins from the old one, so strikingly provided in the opening chapters of the Book of Genesis. Such an account is remarkably “conventionalist,” in that it takes its bearings from solitary or semi-solitary individuals in the state of nature who are in no way political animals by nature. And Locke, a most canny writer, presented arguments in his Second Treatise of Government for human beings being both the product of Divine workmanship and beings who own themselves. Human beings have duties in the state of nature (contra Hobbes) but only when these are not at odds with the overwhelming imperative of self-preservation. For Locke, God and nature are not particularly provident, 9/10, nay 999/1000, Locke says, of what human beings have is the product of human industriousness. In numerous and subtle ways, Locke undermines the multiple reasons why human beings ought to be grateful to a loving and Provident God and a beneficent natural order.I don't like the term "mishmash" because it suggests incoherence. Rather, I prefer "synthesis." In good faith, America's founders, good Whigs they, attempted to "harmonize" (see Thomas Jefferson to Henry Lee, May 8, 1825).
We can discuss whether Locke's teachings were properly "Christianized"* with tips of the hat to the Anglican Thomist, Richard Hooker. Yes, Locke's ideas were presented, often from pulpits, in a manner that suggested compatibility with traditional Christianity and the natural law (Aristotle-Thomism-Hooker); but also often included the "state of nature/social contracts and rights" speak that is, as Leo Strauss put it, "wholly alien" to not only the Bible but also the traditional natural law.
Allan Bloom, one of Strauss' disciples, has an instructive quotation:
When Bishops, a generation after Hobbes’s death, almost naturally spoke the language of the state of nature, contract and rights, it was clear that he had defeated the ecclesiastical authorities, who were no longer able to understand themselves as they once had. ("The Closing of the American Mind," 41-2).Note that it was not Hobbes who was cited from the pulpits, but either Locke explicitly, or Locke's ideas on the state of nature/social contract and rights, without attribution. Bloom, like Strauss before him and Deenen and others, operate under the assumption that Locke was "Hobbesian." We need not operate under this assumption, but rather simply note Hobbes, Locke and Rousseau all shared the common ground of the construct of the "state of nature/social contract and rights," and each had his own particular spin on that construct. It was, for lack of a better term, the "common parlance" among them. This construct was, however, first initiated by Hobbes.
*Meaning the traditional or orthodox practice of the faith.