Perhaps I should expand on something I wrote about the hexeteuch, Genesis through Joshua:
The Penteteuch refers to the first five books of the Bible, commonly called the books of Moses. (I suspect that Genesis is a compilation of ten books written earlier than Moses but which come to us through Moses). The Hexeteuch refers to the first six. It is rather easy to see the Penteteuch as the first “Old Testament” and then Joshua as the first “New Testament.”
Of course, it can be divided more finely: One could see Genesis as the first OT and then Exodus through Joshua as the fulfillment record–the NT.
Or one could take all the books of Genesis except the last one (Genesis 1.1-37.1) as the first OT and then the story of Joseph in Egypt as the fulfillment. For it was the beginning of the fulfillment of God’s covenant with Abraham in Genesis 15.
Despite the qualifications I make, I still think the most obvious way to interpret the Hexeteuch is with the Penteteuch as the first OT and Joshua as the first NT.
In fact, the transition from Moses to Joshua is treated in the Gospels as a pattern for for the transfer between John the Baptist (the greatest of the prophets) to Jesus, as I wrote in 1997:
John the Baptist as the Final Moses
Let’s start with some seemingly random observations about John the Baptist. Notice that John confronts a king (Matt 14:3; Mark 6:17; Luke 3:19) and stays in the region of the Jordan (Matt 3:5; Luke 3:3) in the wilderness (Mark 1:4) across from the Promised Land (John 1:28; 10:40).
Now a few of these details do remind us of Elijah. He too confronted an evil king (1 Kin 17:1; 21:17-19) and spent a lot of time outside of Israel proper (1 Kin 17:3, 9). But he also did more. He called down plagues on the Land (1 Kin 17:1), called down fire on his sacrifice (1 Kin 18:38), was fed by angels in the wilderness (1 Kin 19:4-7), and met God at Mt. Sinai (1 Kin 19:8-14).
I don’t think it is too hard for people who know their Bibles at all to begin thinking about Moses when they notice these things. Moses confronted Pharaoh and called down plagues on Egypt. Also, he’s the first person in the Bible to call down fire from Heaven onto an altar (Lev 9:24).
So far, this has been pretty sparse, but I do think that Elijah stands out among Old Testament prophets as a new Moses. No one else I know of was met by God at Mt. Sinai. It is a unique marker in the Bible. Incidentally, both Moses and Elijah end their careers by ascending-Moses up a mountain to die and Elijah in a fiery chariot. In both cases, this happened across the Jordan from Jericho (Deut 34:1; 2 Kin 2:4-8).
There is more to the connection between Moses and Elijah and John, however, when we consider their successors.
Jesus the Greater Joshua
Elisha accompanied Elijah when he crossed the Jordan from Jericho (2 Kin 2:4-8; 15). When he ascended into Heaven, Elisha was granted a “double portion” of his spirit (2 Kin 2:9-11). Elisha then walked through the Jordan on dry ground (2 Kin 2:14)
Centuries earlier Joshua walked through the Jordan on dry ground, leading the Israelites into the promised land to conquer Jericho (Josh 3:14-17; 6). Just as Elisha was Elijah’s successor, Joshua was Moses’ successor. Furthermore, before Moses had ascended to his death, he laid his hands on Joshua so that he “was filled with the spirit of wisdom” (Deut 34:9; Num 27:18-23). Moses also prophetically gave Joshua his new name, which had originally been Hoshea (Num 13:16).
The similarities between Elisha and Joshua also show interesting redemptive-historical contrasts. Elisha, too, marched through parted waters to Jericho. But he miraculously healed the water there so it was fit to drink (2 Kin 2:19-22).
Now in the Gospels, Jesus goes to the Jordan to be baptized by John, and there the Spirit comes upon Him visibly (Matt 3:13-17). Like Moses and Elijah before him, John says that he must become lesser as Jesus becomes greater (John 3:26-30). Just as Joshua entered the Promised Land, leaving Moses behind, and just as Elisha re-entered the Promised Land with a double-portion of the Spirit, so Jesus as the true successor to Moses and all the prophets begins His ministry after being baptized by John (see Matt 11:7-15). Jesus is the true Joshua, going into Israel conquering and to conquer–though here we see an even greater transition from wrath to grace since Jesus conquests were over demons and disease by His word and Spirit, not over people by fire and sword as was done by the first Joshua.
So the generation that Joshua lead over the Jordan had the five books of the recently-departed Moses. A few decades later, when Joshua was ready to die, they received another book which detailed the history of how God had fulfilled the promises made by Abraham, Isaac, Jacob, and Moses, by giving them the land.
That is what I meant by saying that “It is rather easy to see the Penteteuch as the first ‘Old Testament’ and then Joshua as the first ‘New Testament.’”
But we can go further. For a three centuries or more, the Hexeteuch was Israel’s Scripture. But eventually God started to transform Israel, beginning with the Prophet Samuel. He writes a history of Israel’s decline (Judges), a vindication of God’s faithfulness to the tribe of Judah to provide a king (Ruth), and the story of the establishment of Israel’s Monarchy (First and Second Samuel–finished by Samuel’s successor).
These were new books written by God’s inspiration for Israel.
But there was more. In addition to these books on Israel’s history, other kinds of literature were written for Israel by God’s inspiration. Before Second Samuel was completed, David and Korah and others began writing Psalms.
God’s work in Israel included not only establishing a royal dynasty for Israel but living among them in a new way, in a palace rather than a tent. So the history continues in the book of kings, recording Solomon’s construction project and then the failure of him and his sons to fulfill their duties. Thus we have First and Second Kings, taking us up through the exile of Israel.
And with the reign of Solomon came other literature to add to the Psalms: Proverbs, Ecclesiastes, Canticles, and probably Job at this point.
Let’s stop here for a moment.
During the years leading up to exile in Assyria (Northern Kingdom) and then Babylon (Southern Kingdom), an Israelite had a body of literature consisting of an earlier period an (Hexeteuch) and one from a more recent period. There was an “Old Testament” setting up a confederation of tribes under judges. Then there was a “New Testament” setting up the present order of Monarchy with a Temple and orders of choirs and other new developments.
And this second body of literature breaks down rather easily into two types of work: a history of what happened and documents from that history. This should seem familiar to us. What we call “the New Testament” also has the same types. The four Gospels and Acts give us the history of Jesus and the beginning of the Christian Church establishing a new order; and the documents produced during that history: the letters of Paul and otherr NT writers.
Now lets return to Israel’s exile.
When God brought Israel back from exile, a new history was inspired. First and Second Chronicles are a new version of the history of the kings, and then Nehemiah, Ezra, and Esther. Leading up to that period we have the prophets.
This is rough. For all I know, Isaiah was recognized as Scripture before the Exile.
But, roughly speaking, it seems quite possible that we should view the Bible not as two testaments, but as four–four groups of literature that come from periods of time that are separated from one another. In each of these times God creates a new order and leaves the old behind.
As the final “Testament,” the Greek Scriptures understandably view all that came before as what was left behind. But to understand that older history fully, we should realize that it was not all the same. It involved transfiguration. Indeed, these transformations were themselves not only necessary preconditions leading up to what God finally did on Christmas and then Easter and then Pentecost. They were also prophecies, types of the final Returne from Exile and final Exodus that God would bring about through Jesus Christ.