Who was the author of the first five books of the Old testament?
Genesis opens with God creating the universe. But no one was around when this happened. So, who was the mysterious human author of this portion of the Bible? Historically, Jews and Christians alike have held that Moses was the primary author/compiler of the first five books of the Old Testament. These first five books are often called the Pentateuch. The word "Pentateuch" is from two words--penta--like in pentagon. Penta means five, and teuch means scroll. It means the five scrolls, because these are the first five books of the Old Testament. The Jews called it the Torah, and in the New Testament it’s called the Law.
In the New Testament when you read a phrase, “The Law and the Prophets,” it’s referring to these first five books. They’re essentially the work of Moses. Now, he didn’t write every word in the Pentateuch. We know that, for instance, because Deuteronomy records the death of Moses. Obviously he did not write about that.
Numbers 12:3 has this statement, “Now Moses was a very humble man, more humble than anyone else on the face of the earth.” There is obviously an editor-type involved at this point because certainly Moses would not write of himself, “I was a very humble man, more humble than anyone.”
So the authorship of the first five books of the Bible (Genesis, Exodus, Leviticus, Numbers, Deuteronomy) are basically associated with Moses. As you read through these books think of them as essentially one book with five divisions.