Part of the wonder of Christmas is God saying that the way things are not the way they should be and he's going to do something about it. Isaiah says it like this: Every valley shall be lifted up, and every mountain and hill shall become level; the uneven ground shall become level, and the rough places a plain. Part of how Luke teaches us this is the way John the Baptist comes into the world, preparing the way for Jesus. His parents are barren, long desiring a child. And God does the miraculous, saying again to us that his power is made perfect in our weakness.