Here is a great article by Harvey C. Mansfield on understanding America's philosopher, John Locke, and the relationship between his ideas and our Founding. Locke is extremely easy to take out of context; so, to understand his ideas, it's important to think hard about what he wrote, his contradictions, how to perhaps resolve those contradictions, and the context of the times in which he wrote.
Depending upon one's interpretation, Locke was either a Christian who grounded his arguments for liberty and equality in religious terms, or a secular philosopher who wanted to transgress revealed Christianity. Mansfield endorses the Straussian account of Locke as a "modern" philosopher, which is closer to the latter view. He especially focuses on the problem of reconciling liberty and virtue, specifically Christian virtue. The paradox is this: The Bible tells men how to live. If we only have the liberty to do what the Bible approves, that's not a meaninful understanding of the concept. And keep in mind, Locke helped bring us out of a time when Church and State were one, and when it was viewed as entirely proper to write the Bible and Church doctrine wholesale into the civil law. Mansfield writes:
For Locke, then, the harmonizing of liberty and virtue begins from the harmonizing of liberty and religion. In the face of the apparent fact that the Christian religion tells men how to live, he must show, if he can, that it actually permits them to live in freedom. How does he proceed?
Locke gives two descriptions of the character of men in their fundamental relation to liberty. He says that they are the “workmanship” of God, that men are “his [God’s] property” and so belong to God; but he also says that “every man has a property in his own person.”1 These appear to be directly contrary because the “workmanship argument” (as it is called by Locke’s interpreters) would make man a slave of God2 whereas the idea of property in one’s own person sets him free to do with himself what he wishes. Thus Locke says, in accordance with the former, that men have no right to commit suicide (“everyone is bound . . . not to quit his Station wilfully”3). But in accordance with the latter, though saying nothing directly about a right of suicide, he pronounces that in the state of nature, man is “absolute lord of his own person and possessions.”4 Yet Locke does not make a point of the contradiction between these two descriptions. It is rather as if he had forgotten what he said earlier or perhaps lost his train of thought. Yet Locke does not seem to be a woolly-minded fellow, and his reputation shows that both his friends and his enemies take him seriously. His political thought typically contains contradictions, of which this one is perhaps the most important, but he leaves the reader to do the work of establishing the contradictions and working out their implications. In this case and in other cases, Locke does not leave the contradiction as flat as I have reported it; he teases readers with possible routes by which it might be harmonized.5 But most of all, Locke lets readers do their own harmonizing by allowing them to combine two things they want to believe. Almost all of Locke’s readers would want to believe in the truth of Scripture, and many of them would like to think, or might be persuaded to think, that their belief is compatible with, or even entails, the notion of liberty that Locke sets forth.
The difference between belonging to God and belonging to yourself is not a small one....
Strauss argued that Locke was imbibed in Hobbes and essentially needed to sell Hobbes's ideas to a Christian audience. Locke argued contra Filmer, the leading defender of Divine Right of Kings, who explictly grounded his argument in orthodox Christian terms. Strauss correctly notes that Hobbes's and Locke's "state of nature" theory, which is absolutely fundamental to the philosophy of the Founding, is "wholly alien to the Bible."
Tying this to the deist/unitarian-orthodox Christian debate on the Founders' personal religious views, I've seen it argued that even those Founders like Franklin, Jefferson, and Paine, who clearly weren't orthodox Christians (and who were essential to the Revolution) made Biblical allusions and arguments that were consistent with Christianity. Perhaps they did; after all, they needed to get the institutional forces of Christianity on board against the British. But the converse is also true. There are Founders whom we would place in the "orthodox Christian" box like Patrick Henry, John Witherspoon, and others, who, in their arguments, spoke in the language of state of nature/social contract and rights -- in other words, Christians who made Hobbsean/Lockean, Enlightenment arguments.
As Allan Bloom put it in The Closing of the American Mind:
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. pp. 141-2.