For many Eastern Christians, January 6 marks the feast of Theophany. In the Western Church, this can be a peculiar name, confusing to understand.
What is the Theophany?
The Greek word comes from the combination of theos (God)and phainein (cause to appear, show or bring to light). It is often defined as the appearance or manifestation of God to humanity. (The more familiar Western name for this feast, Epiphany, shares the Greek root phainen.)
For the early Christians, this was primarily associated with Christ's baptism, when God manifested himself to St. John the Baptist and the crowd looking on from the shore of the Jordan river.
Now when all the people were baptized, and when Jesus also had been baptized and was praying, the heaven was opened, and the Holy Spirit descended upon him in bodily form, as a dove, and a voice came from heaven, “Thou art my beloved Son; with thee I am well pleased.”
Early Church Fathers such as St. John Chrysostom solidified this association and the Eastern Church would eventually celebrate this "theophany" on January 6. The Baptism of the Lord is celebrated on a separate day, usually on a Sunday in January, in the Western Church.
At the same time, there was an early tradition of celebrating the birth of Christ (the first theophany) on January 6 as well, but it eventually received a separate feast on December 25.
Then January 6 became associated with a third theophany, the manifestation of God to the magi. The Western Church hung on to this theophany and continues to celebrate it on January 6 under the name Epiphany.
The Theophany is a beautiful feast, one which commemorates the appearance of God to humanity and his great mercy to all people.