What is this guy advocating, making Christianity and/or Catholicism the state religion? This is supposed to be better than an Islamic-law state?
First of all you are confusing a state religion with a religious state, what the piece refers to is restoring the social kingship of Christ as it existed in the Middle Ages prior to the supremcy of the state in the social order.
Secondly, the differences are many and varied. You cannot compare the social kingship of Christ with a state dominated by an heretical religious doctrine such as Islam or even a denomination of Protestantism.
Of course such a thing as an Islamic theocracy leads to tyranny and atrocity, error begats error and evil begats evil.