Civil Centralization = Religious Centralization
“Up to the last, Babylonian religion remained local. It was this local character that gives us the key to its origin and history, and explains much that would otherwise seem inconsistent and obscure.
The endeavour of Nabonidos to undermine its local character and to create a universal religion for a centralised Babylonia, was deeply resented by both priests and people, and ushered in the fall of the Babylonian empire. The fundamental religious idea which had underlain the empire had been the supremacy of Merodach, the god of Babylon, over all other gods, not the absorption of the deities of the subject nations into a common cult.
The policy of Nabonidos, therefore, which aimed at making Merodach, not primus inter pares, but absolute lord of captive or vassal deities, shocked the prejudices of the Babylonian people, and eventually proved fatal to its author.
In Cyrus, accordingly, the politic restorer of the captive populations and their gods to their old homes, the priests and worshippers of the local divinities saw the pious adherent of the ancient forms of faith, and the real favourite of Merodach himself.
Merodach had not consented to the revolutionary policy of Nabonidos; he had, on the contrary, sympathised with the wrongs of his brother gods in Babylonia and throughout the world, and had thus deserted his own city and the renegade monarch who ruled over it.
In all this there is a sharp contrast to the main religious conception which subsequently held sway over the Persian empire, as well as to that which was proclaimed by the prophets of Judah, and in the reforms of Hezekiah and Josiah was carried out practically by the Jewish kings. The Ahura-mazda whom Dareios invokes on the rock of Behistun is not only the lord of the gods, he is a lord who will not brook another god by his side.
The supreme god of the Persian monarch is as absolute as the Persian monarch himself. In the Persian empire which was organised by Dareios, centralisation became for the first time a recognised and undisputed fact, and political centralisation went hand-in-hand with religious centralisation as well.
In Judah, a theocracy was established on the ruins of the old beliefs which had connected certain localities with certain forms of divinity, and which found such naive expression in the words of David to Saul (1 Samuel xxvi. 19): “They have driven me out this day from abiding in the inheritance of the Lord, saying, Go, serve other gods.”
The destruction of the high-places and the concentration of the worship of Yahveh in Jerusalem, was followed by the ever-increasing conviction that Yahveh was not only a jealous God who would allow none other gods besides Himself; He was also a God who claimed dominion over the whole world.”
A.H. Sayce, Lectures on the Origin and Growth of Religion as Illustrated by the Religion of the Ancient Babylonians, 5th ed., London, 1898, pp. 89-90.