Christmas comes each year to draw people in from the chill of heartbreak, disappointment, and loneliness. God draws people in with his promises. When God promises, he will do it, but only in his time and in his way.
God delights to do the impossible, like the virginal conception, because “nothing will be impossible with God” (Luke 1:37). God became man in order to be God with us (Matthew 1:23).
When Mary heard the announcement that she would have a child, she had questions. She knows she cannot yet conceive a child since she is a virgin. She asks, "How will this be?" The answer comes from God and his overshadowing power. "Nothing is impossible with God." Mary simply responds in humble acceptance, "I am the Lord's servant. May it be to me as you have said."
Consider the author of Hebrews 10:5-9:
5 Therefore, when Christ came into the world, he said:
“Sacrifice and offering you did not desire,
but a body you prepared for me;
6 with burnt offerings and sin offerings
you were not pleased.
7 Then I said, ‘Here I am—it is written about me in the scroll—
I have come to do your will, my God.’”
8 First he said, “Sacrifices and offerings, burnt offerings and sin offerings you did not desire, nor were you pleased with them”—though they were offered in accordance with the law. 9 Then he said, “Here I am, I have come to do your will.” He sets aside the first to establish the second. 10 And by that will, we have been made holy through the sacrifice of the body of Jesus Christ once for all.
It was possible! God the Son was born as a baby, grew as a human being, and walked this earth as a man. God provided the way for our sins to be forgiven: “a body you prepared for me.” God did the impossible! This is hope from Christmas.