Jesus stands at the door knocking. In total reality, he comes in the form of the beggar, of the dissolute human child in ragged clothes, asking for help. He confronts you in every person that you meet. As long as there are people, Christ will walk the earth as your neighbor, as the one through whom God calls you, speaks to you, makes demands on you.
That is the great seriousness and great blessedness of the Advent message. Christ is standing at the door; he lives in the form of a human being among us. Do you want to close the door or open it?
God is in the Manger: Reflections on Advent and Christmas
(Westminster John Knox Press; 2010)