Cobweb, I don't have any specific book to recommend. It's just my observation after reading books listening or watching shows on different subjects etc.
Christian ideas and thoughts were not original, they were taken from mostly Egypt and melded with other pagan teachings. The geeks admit their gods were a copy of the Egyptian pantheon of gods and then Rome copied Greece. There are many stories of early Christians going to Egypt to get ideas and concepts for Christianity from the walls of the temples. When one then looks at the worship of gods like Mithra and Dyonisus one can see how these ideas were added to Christianity. On the cover of the Jesus mysteries book by Timothy Freke there's a picture of a little amulet. This amulet shows Dyonisus being crucified on a cross. Jesus road a donkey in the gospel, in an earlier epic from Phoenicia Ashurah rides a donkey. In the book of Revelations it talks about a judgment of the dead a second death for those that are judge unworthy and they are thrown into the lake of fire. This was copied from the book of the dead . These are just a few of many examples.
Theres nothing new under the sun.