Christmas, as it is now celebrated, evolved out of the “Feast of Lights” also known as “Theophany” (celebrated January 6). Originally this celebrated all that had to do with the Lord’s initial coming and appearing on earth (advent) from His conception in the Virgin Mary, through His birth, presentation 40 days later, being in the Temple at age 12, culminating in His baptism in the Jordan River (with some ancient local churches “tying” Christ at Wedding at Cana immediately following His Baptism expressing the Incarnation being about God’s marriage to us in Jesus). There is evidence that people were actually baptized during Theophany Liturgy as well as Pascha in the early centuries. All of this was celebrated within a 24 hour period form the evening of January 5th to January 6.
Many historians of Christian Worship see the “Feast of Lights” (Epiphany/Theophany) as the “Christianized” version of the Jewish “Feast of Lights” which approximated the time of year now known as Hanukah. Hanukah celebrates the rededication of the Temple in Jerusalem a century and a half before Christ when the Syrian Greek forces were driven out after desecrating the Temple with a statue of Zeus in the Holy of Holies. This was the climax of attempts to destroy Jewish faith and identity. The Temple was hastily rededicated and to the chagrin of the Jewish people there was only enough olive oil to keep the light of Eternal Flame at the Altar lit for a day due to the shortages of the recent war. Miraculously, while some scurried to other regions in the coming week to find oil, the Flame was maintained for the next 7 days without adding extra oil. Scripture sees light as a symbol of God revealing Himself. The 8 day continuous burning light (“8” symbolizes “eternal”) signified God revealing His presence which consecrated the Temple once more by once more in the Temple. (The word “Hanukah” is used in Orthodox liturgical circles when a Church is “dedicated/consecrated” transliterated in Greek as “engehenia”).
Theophany for Christians celebrates the revelation of the one true God as “Person” –the Father seen fully present with and known in His Son by the Holy Spirit. God is revealed as Person in “Community” (with other “Persons”) rather than simply a force. It is not difficult to see how Christians then transferred the Jewish Feast of Hanukah where God’s presence was reflected in one lone oil lamp into its larger understanding of being fully present in the Person of Jesus of Nazareth. It is not only the reality of God with His Son and the Holy Spirit with whom He shares all of His essence, eternity, glory, power, etc, but the revelation of humanity’s purpose and goal. All four Gospels record the Baptism of Jesus. Like the crucifixion and resurrection of Christ, the Baptism reveals both God and salvation of humanity and all creation. Water (e.g. Genesis 1, etc) symbolized birth in Scripture. In the baptism of Jesus, the new and real humanity that God always intended, is birthed and made complete in union with Him. It is not a building, but flesh and blood humanity consecrated to be the dwelling place of God. In the human Jesus in whom God is embodied and “immersed,” our humanity is “immersed”/birthed into the very Communion/Community of the Father with His Son and the Holy Spirit completing a partnership that transforms/restores all creation.
When Christianity became a “religio licito” (legitimate religion) of the Roman Empire in the 4th century, one of the challenges was that the larger masses joining the Church maintained some of their pagan celebrations. One of these was the Saturnalia on December 25. The Bishop of Rome “extracted” the Birth of Jesus from the January 6 overall Theophany celebration, placing it on December 25 (12 days earlier) attempting to “Christianize” the pagan celebrations. A few decades later, St John Chrysostom, was the first in the East to have a simple Liturgy for Christ’s birth on December 25 with the main focus still on January 6 (Theophany) as the Feast of Christ’s coming and appearance. After a few centuries and as the celebrations of December 25 further developed, the conception of Christ in the Theotokos (i.e. “Evangelismos”/Annunciation) was moved “9 months” back (March 25). There is also evidence that Christ’s conception/birth might have additionally been celebrated in conjunction with Pascha/Passover in some churches in Upper Palestine/Lebanon. The “new creation/humanity” “birthed” from the crucified and risen Jesus is prefigured in His conception, birth and baptism. (The knowledge of this practice further added to the speculation that the actual birth of Christ might have indeed been around Passover-“springtime” verses winter).
While western Christendom would heighten the focus on December 25 making January 6 almost anticlimactic, Eastern Christians see it as the reverse. December 25 begins the Theophany Season (aka. “12 days”) culminating in the Baptism. In Orthodox cultures into recent history, gifts were given to family members and friends on St Basil’s Day (January 1; roughly paralleling gift giving on St Nicholas Day, December 6, in the West). The culmination of the celebrations for the Orthodox is still January 6. While “modern” Christmas celebrations (with their corresponding “temples and altars” to driven commercial materialism) begin early and finish on December 25, Orthodox seriously prepare with a light (compared to Lent) Fast period beforehand, seeing the birth of Christ as the beginning of the celebrations (seen both Liturgically and in little things such as keeping up Christmas decorations, etc, through Theophany, if possible waiting till after their homes are blessed).