This dissertation compares the theologies of Roman Catholic Louis-Marie Chauvet (b. 1942) and Reformed Protestant Karl Barth (1886-1968) on the relationship between the Word of God and ecclesial rites (sacraments), and the impact these have upon the founding and formation of Christian faith and identity. Both theologians' works place ethical transformation as logically subsequent though integrally related to the encounter with God's Word in ecclesial worship, but the significance of ecclesial rites differs between them. Barth's ultimate rejection of the sacraments necessitates an analysis of the evolution of his theology on this score. It has also generated significant secondary literature either defending his rejection or accounting for it otherwise. To compare Barth with Chauvet, the first two chapters of this dissertation demonstrates this evolution and several major commentators. Chauvet's work not only attempts to answer Barth's critique, but to incorporate contemporary trends in theology, philosophy, and anthropology in a sacramental interpretation of Christian existence. The third chapter surveys the influences at work in Chauvet's theology and summarizes his sacramental theory. The dissertation compares Barth's and Chauvet's theology on relevant doctrinal loci and the role of ethics, and concludes that their theologies may be seen as complementary. It culminates in an assessment of the particular contributions each makes to sacramental theology, suggestions towards an ecumenical sacramental theology informed by both, and a pastoral evaluation.