Constitutions as Establishments

I've been thinking a little bit about the difference between establishments and disestablishments of religion.  Constitutions serve several functions, but for this post, I'm interested in one in particular: to entrench the idea that there is a law above the state's law -- a law that cannot be changed by ordinary legislation.  Could one say this about established religions in constitutional states?  The argument would be that established religions in constitutional states place the constitutional state above its ordinary law, and they thereby control and restrain (the reach of) ordinary law.  Establishments of religion sacralize the state.  If the claim works, then as a functional matter, one might think of the Constitution as an establishment of "religion" -- understood as that which is higher than ordinary law.  Just to put it intentionally controversially, the Constitution -- and, even more specifically, the First Amendment -- is our establishment.  It enshrines limits on the ordinary power of government, and in the case of the Free Exercise Clause, it can even subordinate the ordinary acts of government to higher law.  And the First Amendment is an establishment inasmuch as it incorporates certain relationships between the state and religion right into the fabric of the governmental structure -- relationships which it then fixes and removes from the purview of ordinary law.  The difference between constitutional states with establishments of religions and those without them is that in the former, God or the gods establish the state, while in the latter, people do.  But in both cases, constitutions 'establish' the (for lack of a better term) sacredness of the state and cement its position above ordinary law.  And so, from this perspective, the opposite of establishment is not so much disestablishment as tyranny.