The early Church fathers celebrated EASTER more for the first three centuries. Sometime in the 4th century people evinced curiosity about Jesus' BIRTH.
Since the date of Jesus' birth is unknown, the early Church fathers CHOSE December 25.
As I recall from my early religious teaching they chose that date because it was just PAST the winter solstice, the longest DARK day of the year, as thus the LIGHT was beginning to last longer.
They likened it to Christ's coming and thus chose the 25th for His birthday.
SOME people even have a cake and sing "Happy Birthday" to Jesus on that day.
There's a very good reason for that: the Resurrection is proof that He is who He said that He is.
And if He is who he said he is, then he can do what he said he would do: save people from sin, giving them life — the Cross is the act that paid for our sins, but the Resurrection is proof that the Cross had that power.
So, let's not forget the traditional Easter greeting: He is Risen!