Celtic religion encompasses the spiritual beliefs and customs of the ancient Celtic people. The Celts, an Indo-European group, saw their cultural and territorial height during the 4th century BC, dominating areas from Britain to Asia Minor. However, from the 3rd century BC, their fortunes began to decline, culminating in Julius Caesar’s conquest of Gaul between 58 and 51 BC, which marked the end of Celtic sovereignty in continental Europe. In Britain and Ireland, the decline unfolded at a slower pace, yet the pressure of political control gradually eroded their traditional cultures. Today, Celtic languages persist primarily on Europe’s western fringes, specifically in limited regions of Ireland, Scotland, Wales, and Brittany, the latter due in part to immigration from Britain from the 4th to the 7th century AD. Thus, it is understandable that the fragmented history of the Celts has influenced the preservation and understanding of their religious beliefs and practices.
Sources of Information
Insights into Celtic religion can primarily be gleaned from two significant types of sources: sculptural monuments linked to the Celts in both continental Europe and Roman Britain, and the insular Celtic literatures that survived from the medieval period. Both categories present challenges regarding their interpretation. Most monuments and their respective inscriptions date back to Roman times, often demonstrating a blend of Celtic and Roman deities. Even when symbols and figures seem to originate from pre-Roman traditions, interpretation is complicated by a lack of preserved mythology literature from that era.
It wasn’t until many centuries later, starting around the 7th century in Ireland and even later in Wales, that the mythological narratives began to be documented in writing. By this time, both regions had undergone Christianization, with monastic scholars acting as the scribes and redactors. The wealth of surviving literature is diverse but is distanced, both temporally and culturally, from its original epigraphic and iconographic counterparts found on the continent. This literature inevitably reflects the selective nature of those who wrote it, as well as the influence of Christian teachings that they encountered. Despite these challenges, it is noteworthy that numerous similarities exist between the insular texts and archaeological evidence from the continent. This overlap is particularly evident through the works of Classical commentators, starting with Poseidonius (circa 135–circa 51 BC), who provided valuable accounts of the Celts based on their observations and those of others.
