The last three decades of Patrick’s life were an era of significant transformation in the West as the Roman Empire definitively ended. Cahill notes that the historical writing on Europe in that era focuses on Rome’s fall while neglecting the changes happening on Europe’s fringes, such as in Ireland. In his view, as former Roman provinces plunged into disorder, Ireland’s warrior society became more "civilized" through Patrick’s Christian mission.

Patrick succeeded in converting the Irish because he Christianized their spiritual values while removing their fear of death and of their ferocious gods. He preached that the Irish could be courageous, a quality that Cahill reiterates as one of their signature virtues, while also living in peace. Patrick, like the Irish pagans, viewed the world as a mystical place, but one that is under the power of a compassionate deity rather than subjected to the whims of the malicious and fickle gods who sought to entrap the heroes of Irish legends.

Christianity offered a spiritual view under which suffering was not permanent. Cahill claims that medieval Christianity was born in Ireland. The apostle to the Irish created a world for the Irish that the Romans could not, because he "could speak believably of the superabundance of a God who in response to humble prayer feeds his lost and wandering people with heavenly manna—and a crew of lost and starving sailors with a herd of very earthly pigs" (131).