Genesis, Exodus, Leviticus, Numbers, and Deuteronomy make up the Pentateuch, which Jewish tradition and internal evidence within the
Bible has indicated was authored by Moses.
Destructive higher criticism would disagree.
Of the 39 books of the Old Testament, scholars and skeptics question these 8 books the most:
Genesis, Exodus, Leviticus, Numbers, Deuteronomy, Joshua,
Isaiah, and Daniel.
The question regarding the authorship of the Pentateuch is significant. The controversy questions the reliability of the Old Testament
and ultimately whether if there is a factual basis for Christianity.