At the centre of the Eucharist liturgy we are called on to proclaim the "mystery of our faith". Using scripture and contemporary theology, this book analyzes this phrase, in particular the word "mystery", to reveal its concrete meaning as a sacrament or symbol of faith. It draws on the work of Josef Jungmann, who concluded from his historical research on the Eucharist that this symbol summarized and recapitulated for the Early Church the Christian faith in its unity and entirety. These words, "the mystery of faith", along with accompanying actions, can function for us today in the same way - as what Karl Rahner calls a "short formula of Christian faith". In its exploration of "the mystery of faith", this work integrates many areas of theology: Christology and soteriology, Church and sacraments, and the Trinity. Through these differing disciplines and the book's own approach, it offers theology students, priests and all adult Catholics a new way of addressing the question of how we live and hand on the mystery of faith.