Celtic religion encompasses the spiritual beliefs and practices of the ancient Celtic people. The Celts, a significant Indo-European group, reached the peak of their cultural and territorial expansion during the 4th century BCE, spreading from the British Isles to Asia Minor. Following the 3rd century BCE, their history witnesses a steady decline, culminating in the loss of independence in continental Europe following Julius Caesar’s conquest of Gaul between 58 and 51 BCE. In Britain and Ireland, this decline was more gradual, but over time, the traditional culture faced erosion from political domination. Presently, Celtic languages are primarily limited to certain regions in western Europe, notably parts of Ireland, Scotland, Wales, and Brittany, the latter being influenced by migrations from Britain between the 4th and 7th centuries CE. Thus, the turbulent history of the Celts has significantly impacted the preservation and documentation of their cultural and religious practices.
Sources of Information
Information about Celtic religion largely comes from two main types of sources: the sculptural monuments linked with Celtic populations in both continental Europe and Roman Britain, and the surviving insular Celtic literature from medieval times. However, interpreting these sources presents challenges. Most monuments and their inscriptions date back to the Roman era and reveal substantial syncretism between Celtic and Roman deities. Even when symbols and figures seem to originate from pre-Roman traditions, understanding them is complex due to the lack of preserved literary mythology from that period.
The process of documenting mythology began much later, around the 7th century in Ireland and even later in Wales. By this time, both regions had undergone Christianization, and the literature was primarily composed by monastic scholars, meaning it is somewhat distanced in time and context from the inscriptions and imagery found in continental Europe. As a result, though the literature is rich and diverse, it reflects the selectivity of its authors and their Christian scholarly influence. Nonetheless, it is noteworthy that there are several consistent themes observed between the insular literature and the archaeological evidence found on the continent. This correlation is particularly evident in writings by Classical commentators, such as Poseidonius (circa 135–circa 51 BCE), who documented their observations regarding the Celts.
