In not too many months from now (at the Easter Vigil), we will once again hear those memorable words: O truly necessary sin of Adam! O happy fault that earned so great, so glorious a Redeemer! These somewhat surprising words can be thought to reflect the conviction that the incarnation was made necessary by human sin, and would not have occurred had our first parents never sinned. However, there is a long tradition going back to at least the thirteenth century that is equally convinced that God would have become incarnate in Jesus, even if human beings had never sinned. Now although this might seem like one of those less than relevant theological controversies rendered moot by the simple fact that we did (and do) sin, it has relevance in understanding the essentially twofold purpose of God becoming human.
The first reason is that the incarnation is God’s wondrously merciful response to human sin. Accordingly, Jesus assumes our human nature in order to take upon himself our sins, and by his cruel death on the cross pays, the debt incurred by our sins. Thus, St. Paul explains to Timothy that there is one mediator between God and the human race, Christ Jesus, himself human, who gave himself as a ransom for all. And in the letter to the Ephesians we read that in Christ we have redemption by his blood, and the forgiveness of our transgressions. However, for those who believe that the incarnation would have occurred even if we had not sinned, God assuming a human nature was seen as necessary for the fullness of God’s self-revelation to us. Thus, for Karl Rahner, the incarnation represents the climax and completion of God’s self-communication—one that would have remained incomplete without the incarnation.
But because we have sinned, God’s assuming our human nature now has this twofold purpose—one being no less important than the other. Accordingly, Jesus didn’t stoically or heroically endure his great suffering and death simply as the necessary payment for our debt of sin, but also to convince us that nothing we could do to him would ever prevent him continuing to love us. Thus, William of Saint Thierry, in addressing God the Father, explains that everything [Christ] did and everything he said on earth, even enduring the insults, the spitting, the buffeting—the cross and the grave—all of this was actually you speaking to us in your Son, appealing to us by your love and stirring up our love for you. William then goes on to add: For you to speak thus in your Son was to bring out in the light of day how much and in what way you loved us, for you did not spare your own Son but delivered him up for us all.
And it is this consideration that makes Adam’s sin a happy fault in revealing the infinite depths of God’s love for us—a revelation that might not have been as complete or entire with a sinless humanity. And thus we see that Christmas, is not only the beginning of our redemption but equally the final unveiling of the depths of God’s love—a love that would not remain distant, a love that desires to dwell with us, and a love that turns even our sins into occasions for opening to his love. May this feast renew in us the joy of knowing that God has come near, and that in Christ, humanity has been forever embraced by the fullness of divine ineffable love.