 Religion has played a significant role in the cultural life of the island since ancient times ( and since the 17th century plantations , has been the focus of political identity and divisions on the island ) . Ireland 's pre @-@ Christian heritage fused with the Celtic Church following the missions of Saint Patrick in the 5th century . The Hiberno @-@ Scottish missions , begun by the Irish monk Saint Columba , spread the Irish vision of Christianity to pagan England and the Frankish Empire . These missions brought written language to an illiterate population of Europe during the Dark Ages that followed the fall of Rome , earning Ireland the sobriquet , " the island of saints and scholars " . 
