Any student of politics has at one point encountered some who scoffed at the medieval concept of the divine right of kings. Actually, you're more than likely to encounter it every other week, particularly if you are interested in political philosophy and theory. I suppose the reasoning is this: The divine right was a system level, institutional, concept that legitimized the rule of the strong over the weak. So it then follows that when the upstart American colonists, and later the upstart French anti-clerical terrorists, did the world a great favour by smashing the hegemony of monarchical rule.
Now all of this is fair - I wouldn't trade my liberal democracy for a medieval monarchy. But then again, there's more to the divine right of kings than just having the final authority over a realm and its subjects. Kings were also expected to live by a certain code of Christian ethics. If a ruler fell afoul of the Catholic Church, ie. Christ-on-Earth, his opponents and his subjects were able to legitimize rebellion against him. So, for example, if a ruler is heavily taxing subjects, or even terrorizing them, it would be possible for this ruler to be justly deposed.
This legitimization of dissent came to a close during the late Renaissance. Niccolo Machiavelli pointed out that a ruler is responsible to himself, and must work to maximize his gains. There was to be no obstacle to his rule. Suddenly, religion became the instrument of the state. This new reality was compounded during the Reformation, when opposition to a prince instantly associated any dissenting voice with the enemies of the state religion. This fomented a new type of dehumanization - of the ruler, and of the subject.
Once the ability of a dissenter to reference a higher moral authority, the Catholic Church, it was open season. For the new Protestant kings and princes, there was no fear of rebuke from Rome. Likewise, for the Catholic rulers, there was considerable leeway. Civil war atrocities could be rationalized, and ecclesial opposition was muted, if not already in outright support. For the first time since the Roman Empire, religion sought legitimacy from the state, rather than vice versa.
So now in our time, we are faced with a state that now believes itself to the sole purveyor of legitimacy. For the state, nothing is sacred but the state. It almost makes you wish for a king again.