For the believer, "Come!" is the quintessential prayer of waiting, a conscious act of faith that our current unhappiness will end: God's plan will prevail, and the angels' promise of "great joy for all the people" (Luke 2:10, NRSV) is available—despite evidence to the contrary—right now.
To the first ones who heard this good news, Immanuel came after what must have seemed an endless agony of waiting. Imagine: a 2,000-year-old promise. Four hundred years since God had spoken at all. When I reenter the accounts of Jesus' arrival in our world, as I do every Advent, I'm struck by Mary's response to it all. Not so much by her famous willingness to "let it be with me according to your word" (Luke 1:38, NRSV) as by the confident song she sang about what had happened.
To her much older relative Elizabeth, an upright woman married to a priest, Mary presented the news of her strange, surely problematic out-of-wedlock pregnancy as proof of God's mercy toward those who fear him and his particular love for humble ones like herself. She rejoiced in the fulfillment of the ancient promises of a redeemer who would scatter the proud, bring down the powerful, lift up the lowly, and fill the hungry with good things. "He has helped his servant Israel," she concluded, "according to the promise he made to our ancestors, to Abraham and to his descendants forever" (Luke 1:54-55, NRSV). The blessings she sang of had not yet come to pass and had been promised generations—centuries, millennia!—before her time to people she never met. Yet, her song is one of pure bliss and sounds utterly real and current and personal.