Here is the passage on how Christianity is not necessarily the source of modernity or the "liberal democracy" that America's Founders established:
Many point to Christianity as the historical force that challenged the ancient world’s inegalitarianism. There is quite a bit of truth to this, but it’s possible to push the case too far. Many ideas that are crucial to the modern political synthesis are nowhere to be found until the seventeenth century at the earliest, and even during that era, the far more typical Christian politics was not John Locke’s, but that of the lesser-known Jacques-Benigne Bossuet, Bishop of Meaux and court preacher to Louis XIV. Bossuet’s Politics Drawn from Holy Scripture made the case that the most natural Christian polity — indeed, the only properly Christian polity — was an absolute monarchy, because the king was an image of God on earth. Christianity certainly taught that there was an inherent dignity to all people, regardless of social station, but it was quite reluctant to challenge the idea of social station itself.
This hits upon an important point: Just about all of us agree that divine right of kings shouldn't be reestablished, that religious liberty is a good policy idea, that heretics shouldn't be burned at the stake and so on. Christendom has come to embrace these ideas (indeed, as far as I know, the first to do so). But the text of the Bible itself and the historic practice of the Christian faith don't clearly demand any of these things.
In other words, divine right of kings, the failure to recognize religious or political liberty, the burning of heretics at the stake (as Calvin did to Servetus) -- all of these are arguably just as authentic expressions (arguably perhaps MORE authentic expressions) of Christian political theology than "republican government," "inalienable rights," "religious liberty," and so on.