This title was first published in 2002. The theology of Irenaeus, and the Demonstration of the Apostolic Preaching in particular, is pivotal in showing the way in which the fathers of the church interpreted scripture and distilled doctrine. The Demonstration is an important hinge showing how the doctrine of the fourth century with its definitive councils and definitions of faith, opens out from the new testament apostolic and evangelical witness. Presenting the full translation of the Demonstration of Irenaeus by Dean Armitage Robinson, this book offers a detailed theological commentary by Canon Iain MacKenzie on this foundational doctrinal text. MacKenzie sets out the main theological themes throughout Irenaeus' work, and explores his method of systematic theology, Athanasius's dependence on Irenaeus, and Irenaeus' influence on doctrine in the fourth century - particularly the works of Athanasius, Basil of Caesarea, Gregory of Nazianzus and Gregory of Nyssa. Highlighting the importance of this second century theologian for theology today, this commentary and theological interpretation offers an incentive to study Irenaeus in the wider development of Christian doctrine as a cardinal figure in the appreciation of systematic theology.