This book describes the Church of Jerusalem, as the mother of all Churches, and its liturgy in the beginnings of Christianity. The main objective of this research is to find, in the primary sources (as the pilgrim Egeria, St. Cyril of Jerusalem, the Armenian and the Georgian Lectionaries), the original elements of the Christian liturgy of the early Church of Jerusalem, in the first five centuries, and to collect the various scattered pieces. The author clarifies the image, and reconstructs, as far as possible, the historical-liturgical picture. By this book we will discover how much the other liturgical traditions of various churches, especially the Church of Rome, have copied the Jerusalemite tradition. The detailed description of the Jerusalemite liturgy, especially for the feasts of the liturgical year, offers us a vivid picture of Jerusalem's unique role in Christian devotion and the mysterious connection between the Christian faith and the land of biblical history. The presentation of the anaphora of St. James will enlighten our understanding of the Eucharistic prayer in all the liturgical traditions, especially Syriac, Byzantine and Roman.