This work investigates the historical and theological boundaries of the first century to determine what can be definitively known about the origins of Judaism and Christianity. Samuel Sandmel, a prominent scholar of Hellenistic Judaism and early Christian history, utilizes his extensive academic background to dissect the primary sources and archaeological evidence available from the period. He argues that much of what is often presented as historical fact regarding the emergence of these two faiths is actually based on later interpretations and theological projections rather than contemporary evidence. By applying a rigorous critical framework, he seeks to separate verifiable historical data from the layers of tradition that have obscured the realities of the first century.

Scholars and students of religious history frequently cite this text for its balanced, cautious approach to the complexities of the first century. Experts highlight the book as a foundational resource for understanding the methodological challenges inherent in studying the intersection of early Judaism and Christianity.