Tertullian was the first Western Christian to write theology, defending Christians against the hostility of the Roman state, as well as arguing against Marcion, Praxeas and theosophical fantasy. A complex thinker, Tertullian has, in the modern era, been rejected by both liberal Christianity and its secular critics. For a long time misquoted and misused, he now calls for sustained analysis and interpretation. This book offers a major reappraisal of his theology and its influence on the shape of the Western Christian tradition.