The pre-Christian era
During pre-Christian times, Celts inhabited the area that is now Switzerland. The Helvetii lived in the area between the Alps and the Jura, although the Allobroges in the Geneva area, the Raurici in the Basel area, the Nantuates, Veragri, Seduni and Uberii in the Rhone Valley, the Lepontii in what is now southern Switzerland and the Raeti in modern-day Graubünden were also “Swiss”.
The official name for Switzerland – Confoederatio Helvetica – bears reference to these Celtic ancestors.
There is hardly any reliable information on religion in Celtic “Switzerland”. At least it is assumed, though, that later Christian feasts like Candlemas, All Saints or Christmas derive from earlier Celtic customs (the festival to celebrate the return of the light at the start of February and obsequies at the beginning of November).