Frederick Buechner, in The Hungering Dark, writes:

Those who believe in God can never in a way be sure of him again. Once they have seen him in a stable, they can never be sure where he will appear or to what lengths he will go or to what ludicrous depths of self-humiliation he will descend in his wild pursuit of man. If the holiness and the awful power and majesty of God were present in this least auspicious of all events, this birth of a peasant's child, then there is no place or time so lowly and earthbound but that holiness can be present there too. And this means that we are never safe, that there is no place where we can hide from God, no place where we are safe from his power to break in two and recreate the human heart because it is just where he seems most helpless that he is most strong, and just where we least expect him that he comes most fully.