This book explores the intricate relationship between oral and written traditions in the development of Jewish and Christian identities. Both Rabbinic Judaism and Early Christianity emerged within cultures deeply rooted in oral transmission, where religious teachings, ethical principles, and communal narratives were preserved and shared through memorization, recitation, and communal practice. As each tradition transitioned to written texts—the Mishnah and Talmud in Judaism, and the New Testament and patristic writings in Christianity—leaders grappled with maintaining the flexibility of oral tradition while ensuring the stability of written authority. The book traces the formation of the Oral Torah in Judaism and the apostolic tradition in Christianity, examining how these foundations shaped each community's approach to scripture, ethics, and communal life. Jewish and Christian authorities found creative ways to integrate oral traditions into their sacred texts, preserving pluralistic interpretation and adaptability. Key practices, such as the Jewish study of Talmud and Christian engagement with creeds and councils, reveal how both communities balanced preservation with openness to reinterpretation across generations.