Even if you make the huge assumption that King David was an historical figure there are still problems with Joe Badens CNN Belief blog post "How King David predicted modern Judaism." One major flaw is that "King David" didn't say or write anything about himself even if he did exist. Every passage related to David in the Bible is attribute to other authors. Most scholars long ago figured out that even the psalms he supposedly penned were most likely written by others after his supposed life time.
As for the "prediction" Badens claims, that is also nonsense. His own writing refutes the notion.
"The Israel we know today is a nation that David created virtually out of thin air. Before David, there were two territories, Israel to the north, and Judah to the south."
How does merging two previously established territories qualify as "virtually out of thin air"? Any King seeking to consolidate power would do the same. That is simply a natural progression of political power that is not innately religious let alone unique to a specific religion. A handful of paragraphs later Badens adds an even more telling comment,
"We tend to think of Israel in biblical terms: the land promised to
Abraham, Isaac and Jacob, the land of the 12 tribes. These concepts were
created in the wake of David’s reign."
So, he admits to certain aspects of the Biblical David being fabricated* but fails to question those elements he's counting on for the pieces main premise. How convenient.
The piece never gets any better. None of it is supported by known history. In some ways it is rather impressive how ignorant and delusion Badens is regarding a number of fields of study. Most of the concepts and themes he brings up can be explored from Archeology, Anthropology, Sociology, Psychology, Theology,... He doesn't managed to adhere to the basic research principles of any of these fields. All of which can provide at least partial insights on the rise and establishment of Judaism. Inconveniently for Badens main point is the fact that Judaism predates the sections of the Bible that David is referenced in. There is also a considerable amount of debate about how different Pre and Post-Temple Judaism really is and whether those differences are as significant as they have traditionally been accepted to be.
*Yet another topic I have commented on previously.
Speaking of Faux History (7-16-11)
Family Values with a side of Indigestion (7/28/12)
"History" in the Bible (3/10/13)