Abstract: This monograph examines the claim that ultimately all people will be saved––i.e. that hell will not be eternal and that God will be ‘all in all’ (1 Cor. 15:28). Many Christians have expressed some form of this belief in universal salvation (sometimes known as universalism, or the apokatastasis), despite the fact that it has rarely been regarded as fully orthodox. The book focuses on the concept of universal salvation in the theology of the fourth-century Cappadocian Father Gregory of Nyssa and the twentieth-century Jesuit theologian Karl Rahner. It undertakes detailed studies of eschatology (theology of the ‘last things’) in Gregory's and Rahner's thought, paying particular attention to their contrasting cultural and intellectual contexts: Gregory was educated in rhetoric and in the philosophy of late antiquity (particularly platonism); Rahner was influenced both by Thomism and by later philosophers such as Kant, Maréchal, and Heidegger. Given the two theologians’ contrasting worldviews, this book asks whether their ideas of universal salvation are fundamentally the same––and whether universalism can be regarded as a genuinely Christian idea. It concludes that although Rahner expressed a hope that all will be saved and Gregory asserted universalism more confidently, both men base their convictions on a profound and orthodox Christian belief in the all-encompassing love of God, which has come to fruition in Jesus Christ and is witnessed to in Scripture. The book's final chapter also compares how each theologian deals with the difficult issues raised by the idea of universal salvation, such as human freedom, punishment, and divine justice. It concludes that while Gregory's answers are sometimes clearer, Rahner's are more nuanced and have a subtlety that fits better with scientific discoveries about human nature, the mind and the development of the world. Finally, the book analyses the differences in the two ideas of universal salvation, asks whether one can speak of a ‘tradition’ of universalism in Christianity and reflects more broadly on the causes of development of Christian doctrine.

Keywords: apokatastasis, development of doctrine, doctrine, eschatology, Gregory of Nyssa, hell, Karl Rahner, tradition, universal salvation, universalism