Why does the Armenian Apostolic Church celebrate the Incarnation on Epiphany rather than Christmas Day?

The Armenian Apostolic Church is unique among ancient Christian traditions for never having adopted the December 25 date for Christmas. Instead, it maintains the older, traditional practice of celebrating the Incarnation—which encompasses the birth of Jesus—exclusively on Epiphany, January 6.1

In the early centuries of Christianity, many Eastern churches celebrated the birth of Jesus on January 6, often in conjunction with his baptism. While the church in Rome began formally celebrating Christmas on December 25 in 336 CE to distinguish the feast or potentially to counter pagan solar festivals, this change was not universally accepted in the East for some time. Because the Armenian Church developed its liturgical traditions independently and remained outside the influence of the Roman and Byzantine shifts toward the December date, it preserved the original association of the Incarnation with the feast of Epiphany.234516