The long, shared history of Christianity and Islam began in the early seventh century AD with a question: Who would inherit the Greco-Roman world of Mediterranean? Sprung from the same source, the two faiths played out over the millennium what historian Stephen O'Shea calls "a sibling rivalry writ very large." Their cataclysmic clashes on the battlefield were balanced by long periods of coexistence and mutual enrichment, and by the end of the sixteenth century the religious boundaries of the modern world were born.

O'Shea chronicles both the meeting of minds and the collisions of armies that marked the interaction of Cross and Crescent in the Middle Ages-the better to understand their apparently intractable conflict today.

"Stephen O'Shea writes books in which he becomes part of the places where his history happened. His eye and his acute sense of place have produced great writing. Sea of Faith is beguiling even when the power of the writing sometimes overwhelms the subject. Others have journeyed through this past, and some of the same places. But O'Shea does it better, and more memorably." -- Globe and Mail

"In this elegant, fast-paced, and judicious cultural and religious history, journalist O'Shea...provides a remarkable glimpse into the origins of the conflicts between Christians and Muslims as well as their once peaceful coexistence." -- Publishers Weekl