A theocracy would protect social conservatism better

Theocracy based on a book of rules would actually protect our rights better than trusting our corrupt and incompetent politicians to pass and repeal our laws under the Doctrine of Parliamentary Supremacy. 

What European kingdoms had was not a theocracy but an ecclessiocracy ie rule by priesthood. Priesthoods not bound by a book of rules accessible to everyone would have absolute power. As we know, power corrupts and absolute power corrupts absolutely.