It is well for any two religious groups to discover what is in common between them. This is unquestionably the most effective way -- the best way -- for individuals of two groups to understand one another's religion, and thus to dissipate whatever lack of appreciation or whatever prejudice may obtain.
The common ground between Judaism and Christianity is extensive, and the relationship between these two faiths is intimate. Not only did Christianity grow out of Judaism, but the daughter religion retained the prolific, beautiful, and highly ethical and spiritual religious literature of the mother. And in Jesus the relationship was both intimate and creative: the religion of Jesus was Judaism. That fact alone demonstrates the debt of Christianity to Judaism.
Yet it is not easy to discover the common ground between Judaism and Christianity. It might be supposed that the shared element of sacred literature would lead to understanding. Usually, however, Moses, the Prophets, and the Writings are, to the Christian, the "Old Testament," a prelude to the ultimate, the New Testament. Christians usually study the Old Testament as Christian literature. Similarly, many adherents of Judaism find their Scripture sufficient, and seldom acquaint themselves with Christian writings.
Understanding the common elements of Judaism and Christianity which are represented in Jesus is particularly difficult. For Christians the task involves adequate acquaintance with and appreciation of "late" Judaism, i.e., the legalistic elements associated with Ezra and his successors. For Jews the task requires acquaintance with both the literature and the history of Christianity. The difficulties tax the best efforts of scholars. Fortunately there have been Jewish and Christian scholars who have devoted themselves to efforts in these fields. One thinks of Claude G. Montefiore, or of Joseph Klausner, and of George F. Moore -- representatives of many, of whom the larger number have come from Judaism.
More is needed. There is pressing need for more scholarly contributions by more specialists. But there is a crying need for work which, itself scholarly in method, standard, and content, addresses itself to nonspecialists in Judaism and in Christianity. Such a work is here presented. Its author and I are friends of many years' standing. We have spent many pleasant hours discussing matters treated in this book. I gladly testify to Dr. Fox's scholarship; his competence is apparent in what he has written. I bear witness to the quality and to the zeal of his religious life. He has been the spiritual leader of large congregations. He is devoted to his faith. A liberal -- that is to say, a free -- religious scholar, he knows and values the religion of Jesus and Jesus himself. He has a concern that liberal Jews and liberal Christians share with him what he has discovered. I also have that concern. Dr. Fox has done me the honor of saying that he has learned something from my books; I delight to regard him as my Rabbi, for I have learned from him. When I was working in the field of New Testament history and literature I perceived that I must know late Judaism. I saw that I could not learn all that I needed to know from . . .