Here’s a pretty fascinating essay on Islam, Catholicism, and economic principles from the standpoint of rule of law. Here’s a snippet, from about halfway through:

Consider that the debate between Protestants and Catholics has always at bottom been about authority: does it lie ultimately in the Church or in the Bible? At first glance it might seem that the Protestant answer is a distinctly Hayekian one: the Bible, rather than the Church or the Pope, ought to be the believer’s guide in all things, and as such the believer might seem to be liberated from the arbitrary will of those holding ecclesiastical power.
But appearances are deceiving. For the Bible does not, of course, in any literal sense interpret itself. And yet each believer, being his own “priest,” is supposed to have direct access to the meaning of the text, without the need for guidance by an authoritative Church.
So what are believers to do when they are not sure what the Bible means, or when they disagree as to its meaning? The standard Protestant answer is that the Holy Spirit will lead the believer into understanding. But what criteria are there for determining exactly what the Spirit is saying, or whether He is really speaking to one at all? Here the believer must inevitably fall back on his own private judgment. The result, notoriously, has been the splintering of Protestantism into thousands of denominations. The Bible ends up saying whatever the individual believer thinks it says — however ill-educated or bigoted that believer might be, and whatever extra-Biblical agenda he may unconsciously be reading into it. Every man becomes, in practice, his own authority — which means, in effect, that there is no authority at all.
There is, that is to say, no rule of law in the religious sphere, but rather sheer lawlessness: the majestic and objective will of God as enshrined in the Bible is imperceptibly transformed into the puny, subjective will of the believer who interprets it.

That’s pretty insightful. Read the whole thing.