Man's greatest gift from the past is to be found in his religious heritage. To be sure, not all that comes from the past is either good or valid for today; the best from that source is priceless. The Bible may be considered an abstract of title to the spiritual heritage that has come to the world through ancient Israel. It is not easy even for the expert to trace the transfers of that inheritance from generation to generation, for the process is often intricate; or to mark its course from one century to another, for the sequence is immensely long and involved; or to verify its passage from one race to others, for the racial factors are easily confused. Nevertheless, the prize to be gained, the best in that heritage, is worthy of ceaseless effort, for it has been lost sight of repeatedly, sometimes for generations, even for centuries. It could be lost forever. In this endeavor we are at the outset concerned with the backgrounds of the Jewish-Christian faith and the conditions required for its correct understanding. It is quite impossible to understand and correctly appraise Christianity without a clear knowledge of Judaism. It is also necessary to realize that Christianity was originally made up of strictly Jewish contributions. This was only natural and to be expected, since its first exponents were Jews who never aspired to be anything else. And while Judaism was the end product of Israelitish development, it by no means follows that it represents the highest achievement of the Israelitish religious genius. On the contrary, Judaism may well mark its lowest common denominator. It was, however, the immediate source from which organized Christianity took its rise. [From the Foreword]