Question: "What is the documentary hypothesis?"
Answer: The documentary hypothesis is essentially an attempt to take the supernatural out of the Pentateuch and to deny its Mosaic authorship. The Red Sea crossing, the manna in the wilderness, the provision of water from a solid rock, etc., are relegated to the area of oral tradition from which it can be “proven” that the miraculous happenings were merely products of imaginative oral traditions and not events that actually happened. The documentary hypothesis, with its JEDP theory, denies that Moses wrote the Pentetuch and instead ascribes its authorship to four (or more) different authors / redactors spread out over several hundreds of years. The documentary hypothesis is liberal theology's attempt to relegate the Penteteuch to a errant collection of oral traditions, thereby calling its veracity into question.
Essentially, the stand of the documentary hypothesis proponents is as follows: Instead of placing the written Pentateuch around 1400 B.C. when Moses died, the time frame has shifted 1,000 years to around 400 B.C., the time when the documentary hypothesis says that the Pentateuch was finished. A thousand-year-old memory, even passed down from generation to generation as faithfully as possible, will change from the original events. Remember, this was the time of the wanderings in the wilderness by the Israelites as a result of their rebellion against God. A journey which should take no more than ten days to a month took forty years to complete because of the Israelites’ rebellion. To finally record this journey some one thousand years after it happened is to invite speculation on the genuineness of the original journey. Liberal theologians have, down through the centuries, tried to weaken the Word of God. Conservative theologians, however, strive to preserve the events of history as they actually occurred.
The question is whether this liberal theological view has any basis in reality. The date for the writing of the Pentateuch is a case in point. Liberal theology dates the five books from 400 B.C. when they were written after the Jewish nation returned to the land of their fathers after their years in captivity. This means that Moses could not possibly have written the Pentateuch, for he died some 1,000 years before the books were supposed to have been written. Yet Jesus, in Mark 12:26, said, "Now about the dead rising—have you not read in the book of Moses, in the account of the bush, how God said to him, 'I am the God of Abraham, the God of Isaac, and the God of Jacob'?" Therefore, Jesus says plainly that Moses wrote the account of the burning bush in Exodus 2:3-6. To put the date of the Pentateuch some 1,000 years after the death of Moses is to deny Jesus’ words, for He specifically ties the authorship of Exodus to Moses.
If Moses actually wrote Exodus, as Jesus says, then the whole documentary hypothesis is disproven, for if there is proof that Moses actually wrote one of the books of the Pentateuch some 1,000 years before the date assigned by the documentary hypothesis, then there is strong evidence that Moses also wrote the other four books of the Pentateuch before his death. Luke, in Acts 3:22, comments on a passage in Deuteronomy 18:15 and credits Moses as being the author of that passage. Paul, in Romans 10:5, talks about the righteousness Moses describes in Leviticus 18:5. This passage actually starts at Leviticus 18:1 and continues to verse 5. So, Paul is testifying that Moses is the author of Leviticus. So far, we have Jesus showing that Moses was the author of Exodus, Luke (in Acts) showing that Moses wrote Deuteronomy, and Paul saying that Moses was the author of Leviticus.
Paul, in 2 Corinthians 13:1, establishes the test that proves beyond doubt the truth of a subject. He said, "In the mouth of two or three witnesses shall every word be established" (KJV). So according to the scriptural test for establishing the truth of any subject, if two or three witnesses declare something to be true, it is true. We have Jesus, Luke, and Paul all testifying that Moses was the author of at least three of the books in the Pentateuch and his authorship for the two remaining books, Genesis and Numbers, could be proven if we took the time to research the authorship of these books as we have done for the three we have proven so far. Therefore, it is with great certainty that we can say Moses actually wrote the Pentateuch and finished it around 1400 B.C., just before his death.
To say that the documentary hypothesis is correct in placing the date of the Pentateuch around 400 B.C., well after the death of Moses, is to call into question the testimonies of Jesus, Luke, and Paul, for all of them testified that Moses had written at least three of the books of the Pentateuch, if not all five. Jewish history and tradition also credits Moses as writing the Pentateuch, giving no support whatsoever to the documentary hypothesis. Remember, the documentary hypothesis is only a hypothesis; it has never been conclusively proven, no matter how many liberal theologians claim that it has been. Were it to have been conclusively proven to be correct, in spite of the witnesses that say otherwise, it would no longer be called an hypothesis, but would be referred to as a proven fact.