Names and time

Today is the day of Pentecost. As someone pointed out, according to the church calendar, time, from this point forward, is named as "days after Pentecost", and this is significant.  The way we name things reveals several things, one of them being levels of importance.  In the Orthodox church, Pentecost is a great holy day, seconded only by Pascha (Easter).  What actually happened at Pentecost and what was communicated cannot be overstated.  The miracle of speaking in tongues was a reversal of the Tower of Babel.  When God looked down upon the efforts of men striving after rebellion, in trying to build a tower to heaven, he confused their language to stop their sinful unity.  Now, at Pentecost, because of Jesus' salvific work, man can, united as one in Jesus Christ, unify and once again enter into God's presence.
I would suggest that the overarching theme of Pentecost is mankind united as the church.  As a united people of God, we once again come to God.  This is simply everything.  That singular event should define our reality, thus the concept of naming our time based on this event.
To flesh out one more aspect, consider... linearly speaking, our life moves forward only in regards to the life of Christ, thus our use of his birth for our yearly calendar.  But cyclically speaking, we rise from the dead with Christ at Pascha, but our cycle of life is from Pentecost, when we join together as the church and move through life together, with the blessing of God and the power of the Holy Spirit.  It's always been about "the people of God."
That's important.