“This is an important contribution by one of the leading voices in American evangelicalism. Sweeney’s ‘evangelical catholic’ approach is serious, well-informed, and judicious. The book is a tour de force with practical consequences for the way the church’s theology is to be studied and lived. Highly recommended for all who seek to acquire more of the church’s mindset.”—Bradley Nassif, professor of biblical and theological studies, Antiochian House of Studies

“Douglas Sweeney loves Christian truth. An expert historian of Protestant Christianity, Sweeney has a keen sense for global currents of faith. He is also a man of Scripture, which he discovers reflected in the creeds of those who have gone before us. In this book, Sweeney takes up the nature of doctrinal ‘development’ as understood by Christians from diverse times and confessional commitments. His winsomely Protestant proposal for an evangelical-catholic approach—normed by Scripture but pliable, interculturally engaged, and open-ended—will foster ecumenical conversation among all those who follow the Lord Jesus.”—Matthew Levering, James N. Jr. and Mary D. Perry Chair of Theology, Mundelein Seminary

“This book is vintage Sweeney—brimming with wisdom, refreshing in its passion for biblical orthodoxy, and rooted in a deep love for the church. Sweeney has much to teach us from key thinkers and episodes in the church across time and space. But most of all, he will restore your faith in the glorious future of Christ’s bride. I cannot recommend this insightful book highly enough!”—Hans Madueme, associate professor of theological studies, Covenant College

“Sweeney makes a deeply persuasive plea for Christians, whether in the pews or in the academy, to attend to the full breadth and depth of the history of Christian doctrine—across time, space, and ecclesial boundaries. But this wise, measured, and beautifully written book does more than make a theoretical case. Sweeney illustrates history of and for the church at its best and gives his readers the background and key concepts they need to join in on the grand adventure.”—Han-luen Kantzer Komline, Marvin and Jerene DeWitt Professor of Theology and Church History, Western Theological Seminary, Holland, Michigan

“The current volume is the first of two in which Douglas Sweeney endeavors to answer such questions as, How do we understand the church being holy, catholic, and apostolic? and What unites all churches in the world, whether those in the past, or those in the present with diverse backgrounds? In this book, Sweeney provides a lucid survey of the development of Christian doctrine. This much-needed study will be beneficial to God’s people, particularly in this day and age in which doctrine has become seemingly obsolete.”—Aihe (Luke) Zheng, academic dean, International Chinese Biblical Seminary in Europe

“Driven by learning and devotion put in service to good history and theology, Sweeney offers here a convincing prologue to his forthcoming global history of Christian doctrine. He engages discerningly with relevant currents in contemporary theology to make the case for the possibility and necessity of global history today. The book treats a wide range of movements and theologians, emphasizing the catholicity of the faith across space and time. Readers will appreciate his open ecumenical posture and even-handed treatment of the teachings of the divided churches. Sweeney speaks convincingly across confessional lines. This is truly a book for all Christians!”—Mickey L. Mattox, Flack Family Foundation Chair in Theology, Hillsdale College

“The Substance of Our Faith is a pastoral and church-leadership gem, illuminating the transformative power of historical doctrine for our faith today. It invites church leaders to embrace the guidance of the Spirit, cherish the authority of Scripture and tradition, and foster communion and connection with the saints, as they shepherd their congregations with wisdom and grace.”—Laurent Mbanda, archbishop and primate of the Anglican Church of Rwanda and bishop of Gasabo Metropolitan Diocese; chairman of GAFCON (Global Anglican Future Conference)

“This book excels in two aspects. First, it stands out in terms of its structured approach, demonstrating a keen dedication to understanding the history of Christian doctrine correctly. The range of materials presented is extensive, encompassing Protestantism, Eastern Orthodoxy, and Roman Catholicism. Second, it considers a perspective on the universal church and the practical aspects of an individual’s faith when seeking to understand the history of Christian doctrine. Sweeney’s proposal to understand the history of Christian doctrine within the context of ‘one church, with the church, and beneath the church’ resonates as the voice of the Lord in an age marked by division, much like today. I strongly recommend giving it a read!”—Nam Joon Kim, author of Busy for Self, Lazy for God; senior pastor of Yullin Church, South Korea

“In an era of specialization (and overspecialization?), this book takes us back to the general scholarship practiced in earlier eras that is sorely lacking today. Written to address those Christians who are suspicious of doctrine as something that only divides, The Substance of Our Faith is aimed primarily at ‘those who want to teach in the churches across time and space.’ Deeply committed to a ‘traditional and global’ Christianity, Sweeney advocates convincingly for a Christianity that is best ‘explained with the whole counsel of God—not the whole counsel of God as imparted in the West, but the whole counsel of God as conveyed by the whole people of God, past and present.’ In particular, Sweeney’s willingness to foray into the neglected Eastern fathers and explore patristics beyond Augustine is a welcome relief. Sweeney’s work is a useful textbook on the development of doctrine, authority, and mission in the global church.”—Rev. Fr. Gregory Edwards, assistant professor of missiology, St. Vladimir’s Orthodox Theological Seminary