Here’s my answer:
Time was important for early Christian worship beyond the weekly Sunday gathering.
The first Christians inherited from their forebears a calendar of Jewish feasts and seasons. Taking this way of arranging the calendar, the early Christians reconfigured it according to their witness to the Risen Christ.
The Christian year quickly became an annual rehearsal of anticipation, incarnation, resurrection and indwelling. Interestingly- and surprising to many North American Christians today who think of Christmas as the most important holy day- the original feasts of the church year were:
Epiphany, when, having been met by the magi, Jesus is glorified by the gentile world.
Easter: when God raises Jesus from the dead.
Pentecost: when God sends the Spirit to indwell the Church and send it into the world.
Perhaps this shouldn’t be surprising considering what the Gospels themselves seem to stress and value. After all, only Matthew and Luke narrate what could be considered conventional ‘nativity’ stories. For all four Gospels, Jesus’ baptism is the catalytic scene, Easter is the lens through which the entire story is read back and Pentecost is, as St Augustine called it, the ‘season of joy.’
As the Church grew and spread further from Jewish soil the Church took care to routinize the Christian year and ground time more firmly in the context of Christ’s story.
By the end of the third century the Christian calendar looked like this:
In just another century though the Christian calendar looked like this:
|Christmas 12.25||Palm Sunday||Ascension|
|Jesus’ Circumcision 1.1||Maundy Thursday||Pentecost|
|Epiphany 1.6||Good Friday|
|Presentation in Temple 2.2||Holy Saturday|
It wasn’t until the 4th century, after Constantine converted to Christianity and effectively made it the established religion of Rome, that the Church started celebrating Christmas. We did so by co-opting the Roman holiday of Saturnalia.
The winners get the holidays, in other words. Christmas was originally not an essential holy day to the Church just as 2/4 of the Gospels do not mention Jesus’ birth.
Recognizing this, it’s important for Christians not to abstract the incarnation out of the larger story the Gospels seek to tell and the early Church first celebrated: the resurrection and ascension of Jesus as Lord and King.