I have been reading the Bible over the past few months, and I'm curious about when the beliefs and practices of Judaism coalesced. There are references and hints in the Bible that suggest the early Israelites followed different beliefs, and that ancient Judaism was a significant break from these traditions. For example, the Israelites often worship other gods and are punished for it, most of the kings are labelled evil because they don't worship Yahweh alone, and in the early biblical books people sacrifice in many different locations instead of at one central location, as Deuteronomy commands.

In the Bible Unearthed, Neil Silberman and Israel Finkelstein argue that King Josiah imposed the core of Deuteronomy (which they say was a newly written book, not the lost law of God) as a new religious orthodoxy. They also note that the book is similar to a vassal treaty between a king (Yahweh) and his vassal state (the kingdom of Judah). Furthermore, in Who Wrote the Bible? Richard Friedman argues the Deuteronomic history was written and compiled during Josiah's reign, and that the Deuteronomist portrays Josiah as the hero who loves Yahweh and will lead his people, with God's blessing, to a glorious future.

However, the first section of Isaiah, which I believe was written during the reign of King Hezekiah (early 700s to late 600s B.C.) is strongly monotheist. This would suggest that an early form of Judaism was practiced before Josiah's reign.

My question is, when did practices and beliefs that we would recognize as an early form of Judaism (monotheism as opposed to polytheism, reverence for the Torah, sacrificing in one temple, etc.) coalesce and come together? Was it during the reign of King Hezekiah of Judah, when he attempted a religious reform of centralization? Was it during the reign of King Josiah, who revived these reforms and is so highly praised by the Deuteronomist? Or during a later period?