FROM AUCTORITAS TO POTESTAS: The Development of Roman Primacy from the Pre-Nicene Era to Vatican I

Every serious conversation between Catholics and Orthodox eventually arrives at the same question: what kind of authority did the bishop of Rome hold in the early church, and what did it become? One side sees a universal jurisdiction present from the beginning, merely clarified over time. The other sees a primacy of honor gradually inflated into a monarchy. Both sides quote the same texts.

From Auctoritas to Potestas cuts through this ancient standoff with a distinction the Romans themselves would have recognized: the difference between auctoritas — the weighty, moral, sought-out authority of a revered senior figure — and potestas , the binding legal power of command. With this lens, the contested episodes of church history suddenly fall into place: the evidence for a real and unique Roman primacy is ancient, and so is the evidence of resistance to its expansion — because they are evidence of two different things.

Writing with scholarly rigor and rare fairness to both sides, Laurent Cleenewerck de Kiev — author of the acclaimed His Broken Body — walks the reader through eight centuries of testimony: Clement and Ignatius, Victor and the Quartodeciman crisis, Cyprian and Stephen, the appeal canons of Sardica, Basil’s frustrated letters to the West, Chrysostom’s appeal to Innocent, the formula of Hormisdas, the condemnation of Pope Honorius, and the fateful collision between Nicholas I and Photius that set the trajectory toward schism. The book engages the strongest contemporary Catholic case — including Erick Ybarra’s The Papacy and the Hertling “communio” thesis — head-on, conceding what should be conceded and answering what can be answered.

In this book, you will learn: Why the bishop of Rome was intervening in other churches well before Constantine — and how those interventions were actually received What Vatican I really defined, in its own Latin, and how “immediate episcopal jurisdiction over all churches” would have sounded to a fourth-century bishop How Apostolic Canon 34 defines what it means for bishops to have a “head” — and why headship in the early church meant relational primacy, not unilateral power What the appeal canons of Sardica granted, recognized, or invented — and why both sides still claim them How Basil the Great, John Chrysostom, and Gregory Nazianzen actually regarded Rome’s authority — in their own words Why the era of Justinian, the Monothelite crisis, and the honor paid to popes like Agatho pushed Roman claims to a new level — and how the East pushed back What Photius accepted about Roman primacy, what he refused, and why there are two rival “Eighth Ecumenical Councils” Whether the ancient church’s communion was a star with Rome at the center — or a mesh of regional networks in which Rome was the weightiest node What the first millennium’s working constitution suggests for Catholic–Orthodox reconciliation today Neither polemic nor whitewash, this is the story of how an authority became a power — told by a scholar who believes the two traditions still share more than what divides them. For readers of church history, students of the Catholic–Orthodox dialogue, and anyone who has ever wondered how one see’s primacy became Christianity’s most consequential dispute.