Thomas Aquinas's classic Treatise on the One God is one of the greatest works ever written in the history of philosophy and theology. During the first half of the twentieth century, philosophy of religion was widely viewed as dead, not even a domain of serious questions but only of 'pseudo-questions.' Surprisingly, not only did the supposed corpse rise from the dead, but religion once again became one of the most active fields of philosophical investigation. The time could not be more fitting for a reinvestigation of Treatise on the One God, which opens the massive Summa theologiae. In this unparalleled exploration of the Treatise's penetrating arguments J. Budziszewski explores and illuminates the text with a luminous line-by-line commentary. Supplemented with thematic discussions, this book discusses not only the Treatise itself, but also its immediate relevance to contemporary thought and issues of the modern world. This work fittingly closes the author's series of commentaries on the Summa Theologiae.

‘If there existed commentaries on all of Aquinas's works that were as intelligent, as clear, as satisfying, and as user-friendly as this one, they would totally ‘corner the market’ and spark a massive Thomistic revival.  Budziszewski has succeeded in carving out a distinctive niche that is neither ‘popular’ in the sense of patronizing nor ‘scholarly’ in the sense of onerous. Like Aquinas himself, he has the rare ability to unite profundity with clarity.’

Peter Kreeft - Professor of Philosophy, Boston College

‘This book goes right to the top of my list of reliable, thoughtful, and user-friendly introductions to Aquinas.’

Michael Pakaluk - Professor of Ethics and Social Philosophy, The Catholic University of America Ordinarius, Pontifical Academy of St. Thomas Aquinas

‘J. Budziszewski has won a permanent place among Thomist expositors. Now, his commentary on what Aquinas teaches about the One God has become available. As its name indicates, theology first of all instructs about God. The author possesses a talent for making thirteenth-century texts sound as if they were written yesterday. Scholars will benefit from Budziszewski’s presentation of the material, as well as students - especially beginners, for whom Aquinas in fact wrote his Summa.’

Romanus Cessario - O. P., Adam Cardinal Maida Professor of Theology, Ave Maria University

‘A friend recently asked me whether he should read Aquinas's Summa on his own.  Given how hard reading Aquinas can be on first dipping into it, I advised him against it.  But dumbed-down versions of the Summa are no use either, since they remove the rich layers of sources and the real power of Aquinas's responses.  Thankfully, Professor Budziszewski's book has resolved the dilemma, and I will be giving this book to my friend.  This profound and readable study makes crystal clear why Aquinas's thought is so relevant and necessary today, for seekers and educated believers as well as for professional philosophers and theologians.’

Matthew Levering - James N. Jr. and Mary D. Perry Chair of Theology, Mundelein Seminary

‘Budziszewski's Commentary on Thomas Aquinas’s Treatise on the One God provides an in-depth, detailed, accessible, and comprehensive commentary on the Summa theologiae's early questions about the Transcendent. I’ve been teaching about Thomas’s views of God for decades, and this commentary is - by far - the best single resource I’ve found on the topic.  Students approaching a Thomistic understanding of God for the first time, as well as experienced instructors, will find invaluable aids to deeper understanding. Budziszewski provides an antidote to the allegation that Thomas is dry and dusty by his witty and winning exposition. In the dialogue of faith and reason, Thomas is a pivotal player. In understanding Thomas, J. Budziszewski is one of our very best guides.  This commentary can be read with great profit by sharp undergraduates, graduate students, as well as by professors of philosophy, religious studies, and intellectual history.’

Christopher Kaczor - Professor and Chair, Department of Philosophy, Loyola Marymount University, and author of Thomas Aquinas on the Cardinal Virtues and Thomas Aquinas on Faith, Hope, and Love

‘This is a remarkable commentary, not only because it is accessible to the non-expert and illuminating to the seasoned scholar, but also because it presents with great clarity the doctrine of the one God in a way that demonstrates the strength of the classical view while revealing the poverty of so many contemporary attempts by both theists and non-theists to domesticate the doctrine so that it can be understood within the limiting categories of modern thought. What we also see in this commentary is the true greatness of the mind of St. Thomas Aquinas: his unmatched ability to navigate with philosophical rigor and deep piety the truths of reason and faith, nature and grace, creature and creator, and composition and simplicity.’

Francis J. Beckwith - Professor of Philosophy, Baylor University