Saint Irenaeus was the first great Christian theologian. Born in Asia Minor in about 130 A.D., he became Bishop of Lyons and died as a martyr early in the third century. His main work, Adversus Haereses (Against the Heresies), is as relevant today as it was eighteen hundred years ago. It is a critique of Gnosticism, the 'anti-body' heresy, which, far from dying out, continues to flourish as the main threat to the Christian faith in our own day. With serenity and good humor, Irenaeus unfolds the unity of God's purpose in creation and redemption, in Old and New Testaments. The flesh and blood which Gnosticism so despised has been assumed by God in the womb of the Virgin Mary, and glorified in the Resurrection and the Eucharist.