The following comes from Scott Hahn at the St. Paul Center for Biblical Theology:
In this Sunday’s readings we hear the voice of the Prophet Zechariah as he delivers difficult oracles from God. The people have returned from exile. Now back in Jerusalem, they face the arduous work of rebuilding the Temple. Zechariah acknowledges their hardships and foresees more obstacles.
But their grief has a purpose. It is a remedy, a penance to heal them—“a fountain to purify from sin and uncleanness.”
Thus purified, the people will be ready to receive the Messiah and usher in a new creation. God promises to “pour out on the house of David and on the inhabitants of Jerusalem a spirit of grace and petition.” So that no one should mistake the identity of the Messiah when He comes, God says through Zechariah: “they shall look on him whom they have thrust through, and they shall mourn for him as one mourns for an only son … a first-born.” That prophecy could be fulfilled in no other than Jesus, the Word made Flesh, the Only-Begotten Son of God, the Crucified.
The day of the Messiah indeed came, with an outpouring of the Spirit. Yet it was a saving event not only for Jerusalem, but for all people. Both Jews and Gentiles could become “children of God,” in St. Paul’s stunning phrase. Now, “There is neither Jew nor Greek … slave nor free … male and female … if you belong to Christ, then you are Abraham’s descendant, heirs according to the promise.”
In light of these readings, Sunday’s Gospel is poignant. Jesus asks his closest friends, ” who do you say that I am?” Peter replies, “The Messiah of God.” Jesus then reveals to them, as Zechariah had foretold, that the Messiah must be “thrust through” and killed and mourned before the Spirit would come forth on Pentecost.
The day has indeed come. Yet still we long for its fullness, and so we pray to God in the Psalm: “for you I long! For you my body yearns; for you my soul thirsts, Like a land parched, lifeless, and without water.”