Phizzy,
I highly recommend the book "Crucible of Faith" by Philip Jenkins. It discusses the sources of Christianity and of that other Abrahamic religion, Islam. This is the book's publicity:
Doug
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In “Crucible of Faith: The ancient revolution that made our modern religious world”, Philip Jenkins describes how the Judeo-Christian tradition we know today was born between 250–50 BC, during the turbulent “Crucible Era”—a time when Jews grappled with overwhelming forces of Hellenization and globalization. As a result, Judaism produced new religious ideas that responded to a changing world.
The revolutionary politics of the 160s BC created an apocalyptic world-view where earthly struggles reveal a cosmic significance, a universe dominated by angels and demons. By the time of the fall of the Temple in 70 AD, concepts that might once have seemed bizarre became normalized—and thus passed on to Christianity and later Islam.