What is considered “religion” today was not necessarily the same thing in the past in all cultures. Ancient gods and their cults with their mythology served ancient nations much as flags, a coat of arms, and the political folklore serve modern societies today (consider American legends such John Henry, Johnny Appleseed, Paul Bunyan, and even fictionalized narratives and events in the lives of George Washington, Abraham Lincoln, and Paul Revere).
Not all gods and their cults were as cohesive to ancient life and culture as others. The worship of YHVH by the Hebrews was at first extremely divisive. Monotheism, and the worship of an invisible deity that had no image was not an immediate crowd pleaser for the Israelites. Even the Scriptures tell of how often the Hebrews employed household gods and embraced idol worship as their neighboring peoples did, even for generations after the Exodus.
It was not until the Davidic dynasty that archeology begins to find support for the mythos of the Nevi'im and the united worship of YHVH. King David appears to have made it his state religion at the expense of all the other Hebrew gods, and a conquest intended to bring the tribes of Israel under the one dynasty and worship of the one God failed when the nation divided into two: Judah and Israel.
A peculiarity is also noticed in that the monotheism of YHVH under Judah was quite different than the formula used for heathen and later pagan deities and their cults. The gods of the Gentiles were made in the image of humans: they were anthropomorphic and were cursed with the same jealousies, vanities, and other failings mortals had to deal with, often mirroring them to their own detriment and the universes they ruled over.
The monotheistic God of Abraham was the opposite. First and foremost this God resembled nothing human, nor was YHVH imagined to have the failings that humans did. There was a vast separation constantly portrayed in the cult between humanity and God, with even the only physical representations of God (the Shekinah and the Ark of the Covenant) hidden from view. No image of this God was possible because unlike pagan deities YHVH was not anthropomorphic. Even in the mythology of God, YHVH is a self-designation that is nothing more than circular reasoning: “I am defined by what I am.” While Xenophanes of Colophon came close to grasping the concept of a single and transcendent deity that was “not at all like mortals in body or mind,” for the most part YHVH didn’t catch on with Gentiles. YHVH hardly caught on with the Jews until after the Babylonian exile.
But it should not be a foregone conclusion that religion was almost universally subscribed to in the ancient world. A University of Cambridge study on ancient history demonstrates that atheism thrived in the ancient world of gods and temples and cult priests and priestesses. Religion may never have been the “default setting” for humanity much as the worship of YHVH was not as useful a tool for national unity as some might suggest.
One must also not excuse the earliest views of YHVH in the Torah and Nevi'im as devoid of all humanistic traits and faults. Often the God of Abraham comes across not too different from the gods of the nations. The sacrificial practices of the Hebrews (which they inherited from their Gentile neighbors) are often attributed to God as is their lack of egalitarian views when it comes to dealing with other races, cultures, and even among the sexes, all of which gets attributed to God as if such behavior is based on instruction is from heaven. The description of battles and their subsequent plundering (which in more often than not is over politicized in favor of the Hebrews, if not outright fictionalized in the name of poetic licence for Biblical narrative purposes) makes YHVH appear outright bloodthirsty and uncaring.
The description of the God of Abraham changes almost overnight with the approach of the exile to Babylon however. The prophets describe a God that doesn’t require the sacrificing of animals or demands the spilling of any type of blood. YHVH of the prophets decries violence, claims that the religious priesthood is corrupt, and teaches that Torah is supposed to come from the heart and not from writings on stone. Even the psalms written in this era have God refusing the slaughter of beasts upon altars, like the prophets demanding personal repentance and faithful justice as offerings instead. Festivals are bemoaned, the Temple is condemned, and even the previous religious view the Hebrews had of God is challenged.
It is in Babylon that the cult of YHVH becomes a religion and becomes the useful tool that preserves the identity of the Jews. Judaism is born, one that teaches the children of Abraham that they neither need to literally possess a land or have a temple or offer sacrifices in order to serve God. A religion of egalitarianism begins to start (albeit painfully slow), and even with the fall of the Second Temple it does its job of preservation.
But is it still necessary? Today the concepts of monotheism in Judaism have evolved far beyond the static representations found in Scripture, so much so that Christianity and Islam which sprung from their cult has not (and may never) catch up. With the introduction and now rapid growth of post-denominational, post-rabbinical Judaism a new jump in monotheistic evolution is happening, and as the gulf widens between Jewish concepts of the God-concept and the still picture of the unchanging God adopted by Muslims and Christians, the line between religion and cultural identity of the Jews blurs. How much is worship of what was once called a deity thousands of years ago and how much makes up the earmarks of a people called the Jews? Is it all religion? Is it all culture? Is it a mixture, indivisible and now something different? And is this something different serving a new purpose yet to be understood until that purpose is served?
And what will happen if the other monotheistic faiths catch up with this evolution of God?