Most historical Jesus and Gospel scholars have supposed that the Jesus and Gospel traditions were unidirectionally transmitted from Judaeo-Palestinian into Hellenistic, from oral into written and from Aramaic into Greek, and never vice versa. However, this book proposes that linguistic milieus of 1st-century Palestine and the Roman Near East were bilingual in Greek and vernacular languages and that the earliest church in Jerusalem was a bilingual Christian community. The study of bilingualism creates fresh insights into the origins of Jesus and Gospel traditions, historical Jesus research and the beginnings of Christianity.