In this work, historian Gregory Riley traces the origins of Christianity beyond its familiar sources in Judaism and in the Hebrew Bible. Journeying off the beaten path, Riley reveals other, lesser-known sources - elements of Greek philosophy and science, Zoroastrianism, and the religions of ancient Mesopotamia and Egypt. "From the very beginning," writes Riley, "there were several varieties of Christians." The differences were greater, perhaps, than those seen in the Christianity of today. Dozens of sects arose in different cities of the first-century Greco-Roman world, all claiming to be the religion of the risen Christ. Ultimately, these early, doctrinally disparate Christianities led to the present-day diversity of the Church.