¶ … Nelson's Complete book of Bible Maps and Charts, the authorship of the first 5 books of the bible is attributed to Moses. This is a common view held by modern, conservative Jews and Christians alike, and is the view, according to Nelson's "There was general agreement regarding Moses' authorship until the 18th century. In the modern period, however, it has often been asserted that behind the Pentateuch... are five separate documents, known as J, E, D, P, and R. that each stem from a variety of periods of Israel's history and which were pieced together late in the Old Testament era into what we know today as the Pentateuch. This theory is known as the Documentary Hypothesis" (p. 4) While it may seem to be a small doctrinal issue to instigate a debate over the authorship which is widely recognized for its historical value, and the establishment of the foundations for the Jewish people's identity, this subject is more important than the casual debate because of the implications which it holds. The biblical writings are considered to be inspired, and a revelation of God's personal dealings with his people. As such the biblical writings hold a unique place in the religious traditions of the Jewish and Christian faiths. If the authorship of these writings is in doubt, then the foundations of the Jewish traditions and the Christian roots which are based in Judaism are also similarly on the shifting sand of socio-political evolution. This perspective is unacceptable to conservative Jews and Christians, thus the authorship of these books is of tremendous scholarly and religious significance.

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Jewish practitioners and conservative Christians look first to the scriptures for answers to their questions, and rely primarily on what the scriptures say about themselves to answer such questions. Throughout the collection of biblical writings, the first 5 books of the bible are ascribed to Moses.
For example, in the Old Testament, the writer Daniel says":

Yea, all Israel have transgressed thy law, even turning aside, that they should not obey thy voice: therefore hath the curse been poured out upon us, and the oath that is written in the Law of Moses the servant of God; for we have sinned against him. 12 and he hath confirmed his words, which he spake against us, and against our judges that judged us, by bringing upon us a great evil; for under the whole heaven hath not been done as hath been done upon Jerusalem. 13

As it is written in the Law of Moses, all this evil is come upon us. (Daniel 9.11-13) In this passage, as in Joshua 1.7, Gods' law, which is another descriptor of the first 5 books of the bible, is assigned to Moses authorship. Similarly, in the New Testament, both writers and recorded words of Jesus point to Moses as the author of the Pentateuch.

But Abraham saith, They have Moses and the prophets; let them hear them. 30 and he said, Nay, father Abraham: but if one go to them from the dead, they will repent. 31 and he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, if one rise from…