Did you ever stop to think about what it is that makes Christianity Christianity? Or put another way, what is it about Christianity that is different from other religions?

As the Church moves this year from November into December, the answer to this question should be obvious. The last Sunday in November is the first Sunday in Advent. Advent is the season of preparation for Christmas. It is that series of four weeks when we look at the long history of God’s actions with humanity and then the Jewish people. It is a season that speaks in an indirect way of the problem of humanity: sin.

Advent tells the story of a God who would not give up on his creation or his people. Even when humanity turned its back on God, God would not turn away. God shapes and directs the flow of history, moving things to just the right point in time, and then God acts.

To a young woman named Mary, the Good News first comes: a son will be born that will save God’s people from their sins. Of course Mary first resists, since she is not married. But this child, though human will have God as his father. This child will be the one to return God’s people to God.

It is the Incarnation, God in human flesh, which lies at the heart of Christianity. Other religions speak of mortals who through arduous labor are elevated to become gods. It is only Christianity that tells of a God who becomes mortal.

It all begins at Advent, when God prepares humanity for the answer to the problem of separation from God. Advent tells us that sin will finally be conquered by a human who is completely obedient to God. This second Adam will succeed where the first Adam failed. This second Adam will restore the face to face relationship between Creator and created. It is Christmas that makes the difference. Christmas lies at the center of Christianity: God becomes human. Because of Christmas, everything else is possible. Christmas is at the heart and center of Christianity.