People are generally surprised by God. He knows what He is doing, He keeps His timetable, it ALWAYS seems to surprise and confound us. We are like the historic people of the Bible.
Zechariah, Mary, Elizabeth, Joseph, (Abraham, David, pick a disciple...)
God's messengers show up, and the person (who encounters the place where heaven breaches this world) is encouraged not to fear. Because we are terrified by how much the reality of heaven dwarfs this world.
SO the bigger than big, God of Creation condescends to put on flesh (incarnation) and walks among us in a people-suit. Teaching mercy and forgiveness of sin; teaching the surety of judgement of sin; preaching repentance and discipleship.
It all starts with creation, and culminates in the cross, and flowers through this present day. Christmas is the beginning of the cross. God takes on time and space, nailed to our reality, eventually nailed to our mortality. Death is swallowed up by life. Starting with the life of a child in Bethlehem.
Nothing is impossible with God!