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. This event is also known in all religions, by various names: it is the consumption of blessed food and drink, called communion, eucharist, tsog, prasad, kiddush, etc. It is very powerful to celebrate the Eucharist on Christmas Day. You can perform this ritual at home:

• Article: Eucharist: Spiritual Strength Through Blessed Food and Drink
• Video: YouTube

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.

Learn about the real meaning of Christmas:

• Alchemical Symbolism of the Nativity of Christ by Samael Aun Weor
• Christ and the Virgin by Samael Aun Weor
• The Kabbalah of Christmas by Gnostic Instructor
• Kabbalah of Christmas Part Two by Gnostic Instructor
• Light from Darkness by Samael Aun Weor
• The Nativity of Christ by Gnostic Instructor
• Why Give at Christmas?