The document is a sermon about how God can change lives during Advent season even when life seems impossible. It discusses how Zechariah's life was changed when he was visited by an angel who told him that his wife Elizabeth would bear a son despite their old age. It encourages waiting for God's timing, trusting that God will disrupt lives in order to bless, and relying on God's grace even when his promises seem ridiculous. The purpose of Advent is to foster anticipation of God and remember his grace.