The guy that wrote that book had to do some crazy jumping through hoops to make his ideas work. Look up the meaning of Catholic, I think they took ideas from many religions i the empire to finally come up with the Bible then it was changed and changed again. They took ideas from the Osiris cult, Dyonisus cult, Persian religion , the worship of the Cesar etc to come up with Christianity. Also before the Romans the Greeks were trying to stamp out the Jewish religion ie and they put together the Septuagint.
The Bible is a Greek and Roman invention and the writings came from all over the Levant and were changed to reflect the new god they worshipped. The Greeks for example had no problem keeping the word El in the Hebrew Scriptures because to them it represented Zeus and when they conguered Egypt they had no problem with the worship of Amon because they also saw him as Zeus. Same with Osiris he was Dyonisus to them.