Celtic religion encompasses the spiritual beliefs and practices of the ancient Celtic people. This group, an Indo-European civilization, experienced its peak during the 4th century BC, spreading across Europe from Britain to parts of Asia Minor. The subsequent centuries marked a gradual decline, particularly after Julius Caesar’s campaigns in Gaul (58–51 BC), which resulted in the Celtic loss of autonomy on the mainland. While the decay of Celtic culture in Britain and Ireland was more gradual, it eventually succumbed to political domination. This erosion continues to manifest today, as Celtic languages persist only in specific regions in Ireland, Scotland, Wales, and Brittany—the latter influenced by migration from Britain between the 4th and 7th centuries AD. Consequently, the tumultuous history of the Celts has significantly impacted the documentation of their religious and cultural legacy.
Sources of Information
Key information regarding Celtic religion comes from two primary sources: the sculptural artifacts linked to the Celts in both continental Europe and Roman Britain, and the insular Celtic writings that have survived from medieval times. Each source presents its own challenges for interpretation. Many of the sculptures and related inscriptions originate from the Roman era, showcasing a notable syncretism between Celtic and Roman deities. Even when the artistic elements and themes appear rooted in pre-Roman tradition, they remain obscure due to the lack of a surviving mythological literature.
The compilation of mythic traditions into written form began centuries later, starting in the 7th century in Ireland and occurring even later in Wales. By this time, both regions had undergone Christianization, and the monks responsible for transcription often infused their narratives with Christian perspectives. Thus, while the resulting literature is rich and diverse, it is considerably disconnected from the earlier iconographic and epigraphic evidence found on the continent, reflecting both the constraints of the redactors and their ecclesiastical influences. Notably, despite these challenges, there exists a surprising number of similarities between the insular texts and continental findings, especially highlighted by comments from Classical sources dating from Poseidonius (c. 135–c. 51 BC) onward, who documented their observations regarding the Celts.
