I made no assumption -- merely a testable hypothesis, made because you seemed largely to be reacting to the title. A hypothesis which, incidentally, was a bit more valid than presenting a single counterexample to falsify a generalized theory about history. History is not physics or biology ... patterns are rarely so clear cut. And Russian Christianity is slightly different to begin with.
In any case, I can wax on that the groundwork for modern liberalism was quite possibly laid out in the Bible, well before the Magna Carta, and that at the very least it's an idea worth thinking about. But that's beside my main point, which was that even if you disagree with the book author, as the critic largely does, it's not a good idea to blanket ignore anything the premise of which you find incorrect. There was far more to this long essay than a "debunking."
I would replace your cornerstone of liberalism (nothing says the rule of law has to be good law) with my own: political equality. Christianity's original tenet could then be moral equality (after all, rule by decree from god came later) -- the meek shall inherit.
Phrased that way, the ideas are, while not superimposed, certainly not diametrically different. At that point a book about the subject seems not unreasonable.