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.
"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 is not one individual. Christ is not a person, but a cosmic principle that we must assimilate within our physical, psychic, somatic and spiritual nature.
The word Mass refers to one of the seven sacraments of the Gnostic Church, the Sacrament of Communion, through which we receive the help of Christ. Thus, it is very useful to celebrate the Eucharist on Christmas Day. You can perform this ritual at home:
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.
"In these studies of Kabbalah, we need to be practical; there are authors who write marvels, but when one looks at them, one realizes that they have not lived what they have written; they did not experience it in themselves, and that is why they are mistaken. I understand that one must write what one has directly experienced by oneself. I have proceeded in this way for my part."