Celtic Religion

Greek writers of the sixth and fifth centuries BCE spoke of the Keltoi, peoples living beyond the Alps and in the far west. Modern scholars use “Celtic” mainly for a family of languages, which by the late first millennium BCE were spoken from Ireland and Spain to central Europe and even Anatolia, where the Galatians settled. These peoples shared related languages and, in many places, the swirling La Tène art style, but they never formed a single nation, and their religion varied from region to region and century to century.

What makes Celtic religion hard to study is that its followers left almost no written account of it. The druids, according to Caesar, considered it wrong to commit their teaching to writing. What survives falls into four groups. Greek and Roman authors described the Gauls and Britons, often as enemies or as curious barbarians. Inscriptions of the Roman period, mostly in Latin, name local gods. Archaeology reveals sanctuaries, offerings and images. Finally, Irish and Welsh literature, written down by Christian monks from about the seventh century onwards, preserves stories of gods and heroes, but in forms shaped by centuries of retelling and by the writers’ own faith.

This page therefore speaks of Gaulish and British religion, known mainly from the Roman world, and of the Irish tradition, known mainly from medieval texts, without assuming that they were one system.

Hundreds of divine names survive, and most appear only once or in a single region. Many gods belonged to a particular spring, river, mountain or tribe: Sequana was the goddess of the source of the Seine, Sulis of the hot springs at Bath. Some, however, were honoured widely. Caesar, describing the Gauls in Roman terms, said their chief god was “Mercury”, inventor of all the arts, followed by Apollo, Mars, Jupiter and Minerva. Many scholars identify this Mercury with Lugus, whose name lies behind Lugdunum, the Roman Lyon, and who corresponds to the Irish Lug, the god “skilled in many arts”.

The poet Lucan names three Gaulish gods, Teutates, Esus and Taranis, and Roman-period sculpture shows others: Epona riding a horse, triple mother goddesses, and an antlered god seated cross-legged. That antlered god is called Cernunnos today because a damaged inscription reading “[C]ernunnos” labels an antlered figure on the Pillar of the Boatmen, a monument dedicated in Paris in the reign of Tiberius. Whether all antlered figures across Europe were the same god, and whether they bore that name, is unknown.

In Ireland, the medieval texts describe the Túatha Dé Danann, a race of gods who once ruled the island and later withdrew into the hills and mounds. Among them are the Dagda, the war goddess known as the Morrígan, Lug and Brigid. Brigid, patron of poetry, healing and smithcraft, shares her name and her feast at the beginning of February with Saint Brigid of Kildare, and historians debate how far the saint’s legend absorbed the goddess.

Ideas about death and the world beyond are hard to recover. Caesar and other ancient writers were struck by the Celtic teaching that the soul survives and passes into another body, and some claimed that it made Gaulish warriors fearless in battle. Rich burials, such as the wagon grave of a prince at Hochdorf in Germany or the woman buried with a great bronze vessel at Vix in France, suggest that the dead were equipped for a continued existence. Irish literature describes an otherworld reached across the sea or through the burial mounds, a land of feasting and youth where time runs differently, visited by heroes in tales of voyages. How far these medieval pictures reflect pre-Christian belief is uncertain, but they show how strongly the idea of a hidden world near our own shaped Irish imagination.

Caesar describes the druids as a learned class who led sacrifices, settled disputes, taught the young and were exempt from war and taxes. Their pupils, he says, sometimes studied for twenty years, memorising verses. They held an annual assembly in the land of the Carnutes, believed to be the centre of Gaul, and taught that souls pass after death from one body to another. Pliny the Elder adds the famous scene of druids in white robes cutting mistletoe from an oak with a golden sickle and sacrificing two white bulls. These accounts are precious, but they are Roman views: Caesar was conquering Gaul, and some of his information may have come from older Greek writers.

Roman authors also accuse the Gauls and the druids of human sacrifice. Archaeology suggests that some killings did take place in ritual settings, for example at the sanctuary of Ribemont-sur-Ancre and possibly in the case of Lindow Man, a body found in an English bog in 1984, but how often and why remains debated. Most offerings were of animals and objects. At sanctuaries such as Gournay-sur-Aronde, enclosures held sacrificed cattle and displayed weapons, and across Europe swords, shields and cauldrons were laid in rivers and lakes. In Ireland, at Navan Fort, the legendary royal seat of Emain Macha, archaeologists found the remains of a vast round timber building, dated by tree rings to about 95 BCE, which was filled with stones and deliberately burned, probably as a ritual act.

Irish tradition later remembered great seasonal assemblies. Samhain, at the start of November, opened the dark half of the year; Imbolc in February, Beltane in May and Lughnasadh in August marked the others. These festivals are described in medieval texts, and only Samhain has a possible ancient echo in the Gaulish month name on the Coligny calendar.

The religion of Gaul changed fast after Caesar’s conquest in 58–50 BCE. Roman emperors moved against the druids: Pliny says Tiberius suppressed them, and Suetonius credits Claudius with abolishing their religion in Gaul. In Britain, Roman troops attacked Anglesey in 60 CE, an event Tacitus describes vividly. Yet local gods did not vanish. They were given Roman names and Roman-style temples, so that Sulis became Sulis Minerva and Celtic and Roman gods were worshipped side by side. Christianity gradually replaced these cults in the late Roman period.

Ireland, never conquered by Rome, converted in the fifth and sixth centuries through missionaries such as Patrick. There the old gods passed into literature, as kings, heroes and fairy folk of the hills, and Christian scribes kept their stories alive.

Traces remain. Lyon still carries the name of Lugus. Samhain is the Irish word for November, and its date shaped the customs of Halloween. Saint Brigid’s Day falls on 1 February, and since 2023 Ireland has marked it with a public holiday. From the eighteenth century, romantic antiquarians reinvented the druids, and Iolo Morganwg’s bardic Gorsedd still meets in Wales. Modern Druids and Celtic pagans today honour these gods and festivals in their own revived forms.