The word Christmas comes from "Christ-Mass," a celebration at the solar solstice of winter for the rebirth of the solar force in matter. That solar force is called Christ by Christians, but is known by other names in other traditions. Christ is not one individual. Christ is a cosmic principle that we must assimilate within our physical, psychic, somatic and spiritual nature.
"Among the Persians, Christ is Ormuz, Ahura Mazda, the terrible enemy of Ahriman (Satan), which we carry within us. Amongst the Hindus, Krishna is Christ; thus, the gospel of Krishna is very similar to that of Jesus of Nazareth. Among the Egyptians, Christ is Osiris and whosoever incarnated him was in fact an Osirified One. Among the Chinese, the Cosmic Christ is Fu Xi, who composed the I-Ching (The Book of Laws) and who dubbed the Dragon Ministers. Among the Greeks, Christ is called Zeus, Jupiter, the Father of the Gods. Among the Aztecs, Christ is Quetzalcoatl, the Mexican Christ. In the Germanic Edda, Baldur is the Christ who was assassinated by Hodur, God of War, with an arrow made from a twig of mistletoe, etc. We can cite the Cosmic Christ within thousands of ancient texts and old traditions which hail millions of years before Jesus. This invites us to embrace that Christ is a cosmic principle contained within the essential principles of all religions." - Samael Aun Weor, The Perfect Matrimony
Christ Mass is a celebration of the birth of the solar force within us, a feat made possible by living the teachings given by those who already incarnated that force.