Two decades after Adam Welch wrote The Code of Deuteronomy, Martin Noth changed the way we understand Deuteronomy. Noth saw that Deuteronomy is not isolated within the Hebrew Scriptures the way Welch thought it was. To Welch, Deuteronomy had no application in the Judean monarchy. It’s time had passed and the Priestly writings superseded it. It remained only as a deposit of something that had once been in ancient Israel and the Northern Kingdom.
Noth saw that Deuteronomy was not isolated. Someone had edited the whole primary history of Israel from Genesis-Kings to reflect the point of view of Deuteronomy. This editor he called the Deuteronomist. More recently Richard Friedman, who follows Frank Moore Cross’s modification of Noth’s theory, has speculated that this person was Baruch, Jeremiah’s scribe. Since Baruch is a lot easier to say and more concrete than the Deuteronomist, that’s what I will call him here.
Baruch, at the time of the fall of Jerusalem to Babylon, reinterpreted Israel’s whole history as a fulfillment of the warnings and curses in Deuteronomy against disobedience to its laws. Israel disobeyed; this is why the temple fell and the dynasty of David stood imperiled.
This partly depends on seeing that Deuteronomy has a unique style. You can find examples of that style in pieces that look like they have been inserted into the historical books, particularly Joshua and 2 Kings. Also the style of Deuteronomy has influenced the style of Jeremiah, hence the Baruch theory.
Since Deuteronomy’s style has influenced Jeremiah, but not Isaiah, Hosea, or Amos, scholars have reasoned that someone must have written Deuteronomy after those prophets and before Jeremiah. That reasoning excludes some possibilities and does not take account of all the evidence.
Psalm 78, for instance, has something in common with Deuteronomy’s style and seems to come from a time before Hosea.
Welch did not think that the centralization-of-worship passage in Deuteronomy 12:1-7 could have been inserted into the code. He thought it was just another of the disparate laws that made up the code. On the other hand, Welch associated the passage with the final form of Joshua. Now we can see that the final form of Joshua looks like Baruch’s work. So, Welch makes less sense in light of what we now know.
So, very tentatively, I think this may be what happened. A forgotten book was found in the temple during Josiah’s reign. We don’t know the full extent of the book, but it included most of chapters 12-26. Josiah was already engaged in reform (2 Chronicles 34:3-14). This book, however, authorized a blood-purge against idolatrous priests and those who practiced occult arts (2 Kings 23:5, 24). These executions (there may have only been a few) were later seen as Josiah getting serious about reform.
The book that was found did not actually centralize worship. It was not a fraud, but the priests of Jerusalem, who already thought the temple there was special because it was the royal sanctuary and had once– or maybe still– boasted the presence of the old battle ark from Shiloh, presented the king with an interpretation of the book that authorized centralizing the cult. They thought this was needed to deal with widespread religious malpractice.
Baruch wrote that interpretation into the text, implying in 12:1-7 that centralization went back to Joshua and the conquest. This was not entirely without historical basis. People had long made pilgrimages to Jerusalem (1 Kings 12:27). Yet, even in Judah, we know there were worship centers at Arad and Beersheba.
Ephaimites may have tried to make Shechem the preeminent sanctuary at some point. Shiloh may have functioned as pilgrimage center for a while. Jeroboam made sanctuaries at Dan and Bethel preeminent. But Amos mentions other sanctuaries functioning during that period (Amos 5:5). So all acceptable places of worship had never had equal importance.
Welch, I think, was right about authorized Yahwistic shrines having been distributed all over Israel. That the law was about the character of worship more than the place of worship makes sense. His picture of how the Levites functioned in a society centered on clan and village makes sense. His picture of how the laws developed in a community that saw itself standing in the tradition of Moses makes sense. Welch used the code of Deuteronomy to get a picture of what Israelite religion was really like before a centralized priesthood and royal bureaucrats impinged.