The title of Father Edward Oakes’ new book, “Infinity Dwindled to Infancy,” nicely captures the imaginative challenge posed at Christmas: the mystery of the infinite God become finite man. In truth, however, the challenge to our imaginations has less to do with the how of what the Divine Office calls this admirabile commercium (marvelous exchange) than with the why.
Posit an all-powerful and infinite God, and most of us wouldn’t have too much trouble with the idea that such a God could do anything, including coming into the finite world he created. The real question is why such a God would want to do such a thing: to submit his divinity to the limits of our humanity, to dwindle into infancy and then to go farther—to die as a tortured criminal at the hands of his own creatures. Here is the “scandal” of Christianity. For the answer faith gives to the question of why is salvific love: a love so great that it required, not an argument, but a demonstration.
Eastern Christian theology helps us understand the full dimensions of the why of the Incarnation through its concept of theosis, or divinization: God becomes man so that we might become like God—so that we can live comfortably with God forever. Here, then, is the admirabile commercium: God “exchanges” his divinity for our humanity, thus enabling us to “exchange” our weakness for his divine glory—the glory of which the angels sing to the shepherds of Bethlehem. The years St. Paul spent in the desert, pondering just how the Paschal Mystery of Christ’s death and resurrection, which had been revealed to him on the road to Damascus, fulfilled God’s election of Israel, led the Apostle to the Gentiles to be the first to formulate this “exchange”: “For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that by his poverty you might become rich” (2 Cor 8:9).
The Fathers of the Church took up the theme and developed the idea that, in the “exchange,” men and women were empowered to become godlike. Thus St. Gregory Nazianzen: “Let us seek to be like Christ, because Christ also became like us: to become gods through him since he himself, through us, became a man. He took the worst upon himself to make us a gift of the best.” If the language of “becoming gods” strikes our ears as odd, that may be because we have not quite plumbed the radical depths of the divine love: for in the Incarnation, “God so loved the world” (Jn 3:16) that he doubled-down on the divine humility, dwindling himself into infancy so that we could share, really and truly, in the divine life.
The indictment of Christianity that began in the 18th century and metastasized in the 19th was that the God of Abraham, Isaac, Jacob and Jesus kept humanity infantile, such that only by throwing the God of the Bible over the side could humanity ever achieve maturity and liberation. This was, of course, a complete inversion of the truth: the Christian faith, proclaimed by the Second Letter of Peter, is that God, by the Incarnation, has made us “partakers of the divine nature” (2 Pt 1:4). And in doing so, the divine humility, manifest as love, brings us into the fullness of human maturation and the fullness of true freedom. Thus Pope St. Leo the Great, in the Christmas homily the Church reads in the Office of Readings for Christmas Day, could admonish his Roman congregation in 440: “Realize, O Christian, your dignity. Once made a partaker in the divine nature, do not return to your former baseness by a life unworthy of that dignity.”
Christmas faith inspires righteous living, not by fear, but by love: the love that expresses itself in history in the humility of the Incarnation and the Holy Birth; the love that speaks of the glory of God, “wrapped in swaddling clothes and lying in a manger” (Lk 2:12).