What was Christianity?

Everyone knows what Christianity is. Could we be wrong? One way to begin to answer that question is to disregard everything we know about things called Christianity after, say, 28 August 430 CE and ask a focused question: What was Christianity?

This is the keynote lecture for The Writing of Ancient Christianity in Late Antiquity and the Middle Ages, the 2024 UBC Medieval Workshop in tribute to Professor Mark Vessey (Principal Emeritus of Green College).

James (Jim) J. O'Donnell was born in Germany a few miles outside the furthest boundary of the Roman empire and grew up a few miles inside the US-Mexico border in El Paso. He explores the many boundaries that criss-crossed the late antique Mediterranean world in the belief that margins and extremities reveal truths inaccessible elsewhere. His books include biographies of Augustine and Cassiodorus, commentaries on Augustine and Boethius, a translation of Caesar's Gallic War and Avatars of the Word: From Papyrus to Cyberspace. He has been Professor and Vice Provost at the University of Pennsylvania, Provost at Georgetown and now serves as University Librarian at Arizona State University.