Mary, the mother of Christ, I can’t even wrap my mind around that idea, but one of my favorite parts of the Christmas story is her response–often known as The Magnificat–when she learns that she will bear the Son of God. It’s found in Luke 1:46-55

And Mary said:
My soul exalts the
Lord,
And my spirit has
rejoiced in God my
Savior,
For He has had regard
for the humble state of
His bondslave;
For behold, from this time
on all generations will
count me blessed.
For the Mighty One has
done great things for
me;
And holy is His name.
And His mercy is upon
generation after
generation
Toward those who fear
Him
He has done mighty
deeds with his arm;
He has scattered those
who were proud in the
thoughts of their
heart.
He has brought down
rulers from their
thrones,
And has exalted those
who were humble.
He has filled the hungry
with good things;
and sent away the rich
empty-handed.
He has given help to
Israel His servant,
In remembrance of His
mercy,
As he spoke to our
fathers,
To Abraham and his
descendants forever.

Mary is told that her entire life is about to be entirely other than what she had planned, and her response is to praise God; she believes him, that he will do just as he told her. Her faith is not misplaced, because God fulfilled his word, as he always does.
For a much more in-depth look at The Magnificat, check out this article