The Christian Reception of the Hebrew name of God has not previously been described in such detail and over such an extended period. This work places that varied reception within the context of early Jewish and Christian texts; Patristic Studies; Jewish-Christian relationships; Mediaeval thought; the Renaissance and Reformation; the History of Printing; and the development of Christian Hebraism. The contribution of notions of the Tetragrammaton to orthodox doctrines and debates is exposed, as is the contribution its study made to non-orthodox imaginative constructs and theologies. Gnostic, Kabbalistic, Hermetic and magical texts are given equally detailed consideration. There emerge from this sustained and detailed examination several recurring themes concerning the difficulty of naming God, his being and his providence.