Mr.Atwill is a "Josephus scholar" in that he premised his thesis on Josephus's historical accounts in the 1st Century CE. However, Josephus has been proven to be a pseudegraphical personage, invented to buttress the "Ancient Hebrew" thesis or the pretended antiquity of the Hebrew sect. In other words, Josephus never really existed as a historical figure, and Mr. Atwill's book and thesis must be taken with a grain of salt.
Moses as the purported writer of the Torah could not have written the Torah in Hebrew, even if he had lived, because there was no Hebrew script when Moses supposedly lived. I maintain that Moses or Ahmose is a pseudegraphical-Egyptian name that was created by the Greeks to hide the identity of Akhenaton or AmenHotep IV, an Egyptian king famously known to be the father of MONOTHEISM. I further maintain that the Septuagint/Torah/Pentateuch/Old Testament was formulated by the Greeks from the Ancient Egyptian texts, and the New Testament was formulated by the Romans. Before the two books (Old and New Testaments) were combined into one, the followers of the old testament (mostly monophysites) fought the followers of the New Testament (I.e. dyophysites) for nearly 1000 years (see the Crusade). The outcome of this fight led to the fall of the Eastern Roman Empire, and the rise of Mohammedanism in Constantinople, and later Islam.
In other words, Islam in its original form was a form of orthodox Christianity, and remember that before the invention of Jesus by the Romans, there was Serapis in Hellenistic or Coptic Egypt, and before the invention of Separis by the Greeks, there was Ausar(Osiris) the father in Ancient Egypt.
Ladies and gentlemen, the stories of the Hebrew as described in the scriptures are distorted and plagiarized stories of the Ancient Egyptians.