All saints day has an origin that includes the Celtic autumn holiday of Samhain and a similarly themed Roman harvest festival known as Lemuria.
"All Saints Day, otherwise known as All Hallows (hallowed means sanctified or holy), continued the ancient Celtic traditions."
All Saints Day Traditions
"In the Christian calendar, November 1 is the Feast of All Saints, a day honoring not only those who are known and recognized as enlightened souls, but more especially the unknowns, saints who walk beside us unrecognized down the millennia. In Buddhism, we honor the bodhisattvas - saints - who refuse enlightenment and return willingly to the wheel of karma to help other beings. Similarly, in Judaism, anonymous holy men pray the world from its well-merited destruction. We never know who is walking beside us, who is our spiritual teacher. That one - who annoys you so - pretends for a day that he's the one, your personal Obi Wan Kenobi. The first of November is a splendid, subversive holiday."
-Mary Rose O'Reilley, The Barn at the End of the World: The Apprenticeship of a Quaker, Buddhist Shepherd