Christmas is God in human language.
It is about a God who, in loving us, knows how to speak to us.
The Letter to the Hebrews says, "In the past God spoke to our forefathers through the prophets at many times and in various ways, but in these last days he has spoken to us by his Son" (Heb. 1:1-2).
Christmas is revelation, manifestation, showing what was hidden. The Advent cry, "Open up, ye heavens from above!", expresses the human need for meaning, and for the answers to basic questions: Why are we here? What is this life about? Where are we going? Is there life after death? How are we supposed to live? Does God exist, and if so, is he friend or foe? How does he want to be worshipped?
All the philosophers of history, though coming to certain conclusions correctly through human reason (which, though wounded by sin, is not destroyed) nevertheless could not reach the full answers to all these questions. God needed to speak, and he needed to speak in human language.
So the Son, who reveals the Father, has come, and Christmas celebrates that coming. Continuing that passage from Hebrews, which is used by the Church for Christmas Day Mass, we read, "The Son is the radiance of God’s glory and the exact representation of his being" (v. 3).
So, thanks to Christmas, we know who God is, what life is about, what God expects us to do, and what awaits us beyond the grave. We know how to obtain eternal life. We have found what the human heart has always sought. St. John writes, "After this I looked, and there before me was a door standing open in heaven" (Revelation 4:1). Christmas opens that door and shows us God in human language!
Christmas destroys the "tyranny of relativism," the confusion of indifferentism, the idea that each person can create his or her own morality, or that one religion is as good as the next. As we welcome the birth of this child, we welcome the one who will preach the Sermon on the Mount, instruct us by parables, and establish his Church to continue making his teachings clear.
To welcome the Divine Child today is to welcome all that he will do and teach, the easy and the difficult, the comforting and the challenging, without considering ourselves authorized to pick and choose among those teachings.
It makes no sense to welcome the child but reject his teachings. It is inconsistent to prepare for and celebrate Christmas but refuse to accept the fullness of the Gospel that this child proclaimed.
That Gospel has taught from the beginning that life must be protected, including life in the womb. There can be no such thing as a "pro-choice Christian." A rejection of even a single life is a rejection of Christ himself.
This Advent and Christmas, let us welcome Christ and all that he teaches, and all whom he loves.