The world religions we call Judaism and Christianity each received formative influences from the religion of Israel in its interactions with the surrounding societies after its fall to the Babylonian empire, especially with Greece and Rome. Encounters ranging from serious engagement to deadly persecution shaped the features most characteristic of the Abrahamic religions. Through a close, inductive study of a wide variety of ancient texts, ranging from the 2nd century BCE to the 5th century CE, and historical study, we will examine major factors of this transformation, and also consider how it has continued to shape the development and interactions of societies and religions into our own times.