Who wrote it? For some the answer is easy. Jews and Christians have traditionally believed that the prophet Moses wrote the first five books of the Old Testament ... known as the Pentateuch .. or the Torah. Early scholars who hazarded to point out how unlikely it was that certain sections were actually written by Moses – the account of his death, for example – were often ostracized, expelled from their religious order, or forced to recant. Today, many fundamentalist and orthodox religious people continue to believe that the Bible is the true word of God, told through Moses. (p. 28)
Notice how a belief about the Torah at the beginning of the paragraph becomes a belief about the Bible as a whole by the end of it. This is not just one case of sloppy writing; the article is full of this misapprehension. She goes on to talk of doublets "in the Bible," two different names for God "in the Bible," and so on. An account of the Documentary Hypothesis becomes an answer to the question "Who wrote the Bible?"
Now I question whether anyone who has ever cracked open a Bible has ever asked the question, "Who really wrote the Bible?" -- because the Bible is self-evidently a library or anthology of different pieces written at different times. The fiercest fundamentalist and the whackiest liberal are at one on this perception. The answer, historically speaking, is "Lots of people." If you change the terms of the question to "Who wrote the Torah?" -- that's a different story. There are still places where you can get a heated discussion going on that one. But to confound the two questions is to propagate confusion.
I think the culprit -- unwitting, no doubt -- is Richard Friedman's book Who Wrote the Bible? which does deal primarily with the question of the Pentateuch. It's a fine piece of popularization of biblical scholarship, and widely read for good reasons. But, let's face it, a book called "Who Wrote the Torah?" or "Who Wrote the Pentateuch?" or "Who Wrote the First Five Books of the Bible, Traditionally Ascribed to Moses?" or "Who Wrote Part of the Bible?" is not going to sell at all. I have a theory that Friedman's publisher either changed the original title, or talked him into changing it, resulting in a question that is, strictly speaking, nonsense.
Publishers do this sort of thing; I know of one case where a manuscript with the austere but evocative title The Rediscovery of the Dead Sea Scrolls was changed by the publisher to Solving the Mysteries of the Dead Sea Scrolls -- a title that implied as much confusion as Who Wrote the Bible? What can you do?